Add some docs about build-arg's impact on the cache
Add some docs about build-arg's impact on the cache

Closes #18017

Signed-off-by: Doug Davis <ff3bde741799c0eff815b83a54eda3fc494df54f@us.ibm.com>

estesp/docker,Mashimiao/docker,yasiramin10p/moby,noironetworks/docker,denverdino/docker.github.io,cpuguy83/docker,lixiaobing1/docker,tklauser/docker,troy0820/docker.github.io,shubheksha/docker.github.io,ajneu/docker,Ramzec/docker,HuKeping/docker,jecarey/docker,Collinux/docker,konstruktoid/docker-upstream,tianon/docker,duglin/docker,ripcurld0/moby,ibuildthecloud/docker,SvenDowideit/docker,Microsoft/docker,clintonskitson/docker,bdwill/docker.github.io,ajneu/docker,JimGalasyn/docker.github.io,achanda/docker,dongjoon-hyun/docker,kerneltime/docker,sunyuan3/docker,armbuild/docker,charleszheng44/moby,jc-m/docker,TrumanLing/docker,dsheets/moby,djs55/docker,konstruktoid/docker-1,mkumatag/docker,mtrmac/docker,isubuz/docker,hyperhq/hypercli,dgageot/docker,geekylucas/docker,HideoYamauchi/docker,supasate/docker,Collinux/docker,splunk/docker,dbonev/docker,sanjeo/docker,sanscontext/docker.github.io,justincormack/docker,thtanaka/docker,johnstep/moby-moby,HackToday/docker,sanjeo/docker,ibuildthecloud/docker,BrianBland/docker,xiekeyang/docker,14rcole/docker,LuisBosquez/docker.github.io,qudongfang/docker,SvenDowideit/docker,gao-feng/docker,cr7pt0gr4ph7/docker,joaofnfernandes/docker.github.io,jlhawn/docker,Shopify/docker,denverdino/docker.github.io,projectatomic/docker,haugene/docker,alexisbellido/docker.github.io,Ramzec/docker,tonistiigi/docker,joeuo/docker.github.io,pramodhkp/moby,errordeveloper/docker,yosifkit/docker,flavio/docker,thaJeztah/docker.github.io,zhangjianfnst/docker,cpuguy83/docker,sanjeo/docker,shin-/docker.github.io,sheimi/docker,londoncalling/docker.github.io,moypray/docker,docker/docker,darrenstahlmsft/docker,YuPengZTE/docker,OnePaaS/docker,cyphar/docker,BrianBland/docker,dgageot/docker,stainboy/docker,zhuguihua/docker,vincentwoo/docker,alfred-landrum/docker,umerazad/docker,moul/docker,mikebrow/docker,tophj-ibm/docker,bearstech/moby,tpounds/docker,13W/docker,aidanhs/docker,SaiedKazemi/docker,toli/docker,coreos/docker,estesp/docker,bearstech/moby,zelahi/docker,docker/docker.github.io,maxamillion/docker,askb/docker,icaoweiwei/docker,Test-Betta-Inc/psychic-barnacle,pyotr777/docker,johnstep/docker.github.io,imkin/moby,KarthikNayak/docker,allencloud/docker,zhuohual/docker,justyntemme/docker,joaofnfernandes/docker.github.io,erikh/docker,nigelpoulton/docker,hypriot/docker,joaofnfernandes/docker.github.io,msabansal/docker,yangdongsheng/docker,BSWANG/denverdino.github.io,rkazak/docker,umerazad/docker,bonczj/moby-json-file-logger,amatsus/docker,miminar/docker,pradipd/moby,hyperhq/hypercli,mikedanese/docker,ktraghavendra/docker,sterchelen/docker,twaugh/docker,johnstep/docker.github.io,sanscontext/docker.github.io,alexisbellido/docker.github.io,gnailuy/docker,sean-jc/docker,aduermael/docker.github.io,sean-jc/docker,shubheksha/docker.github.io,csfrancis/docker,aaronlehmann/docker,yp-engineering/docker,mathewkoshy493/docker,containers/storage,prertik/docker,SaiedKazemi/docker,clintonskitson/docker,Distrotech/docker,laijs/docker,kyle-wang/docker,prertik/docker,rhatdan/docker,x1022as/docker,akira-baruah/docker,justincormack/docker,cnaize/docker,anortef/docker,mssola/docker,anujbahuguna/docker,paralin/docker,moul/docker,ncdc/docker,errordeveloper/docker,menglingwei/denverdino.github.io,askb/docker,mahak/docker,izarov/docker,BSWANG/denverdino.github.io,joeuo/docker.github.io,darrenstahlmsft/docker,endophage/docker,sdurrheimer/docker,tkopczynski/docker,ajaymdesai/docker,upmio/docker,pmalmgren/docker,menglingwei/denverdino.github.io,ColinHebert/docker,moxiegirl/docker,docker-zh/docker.github.io,gaobrian/docker,ndeloof/docker,POLJM242/docker,JimGalasyn/docker.github.io,catinthesky/docker,kunalkushwaha/docker,ktraghavendra/docker,endocode/docker,aditirajagopal/docker,nawawi/docker,s7v7nislands/docker,konstruktoid/docker-1,HackToday/docker,hqhq/moby,toli/docker,HideoYamauchi/docker,containers/storage,Neverous/docker,thaJeztah/docker,phiroict/docker,ajaymdesai/docker,OnePaaS/docker,alexisbellido/docker.github.io,jloehel/docker,srust/docker,rillig/docker.github.io,anweiss/docker.github.io,POLJM242/docker,icecrime/docker,bluebreezecf/docker,BSWANG/denverdino.github.io,kencochrane/docker,whuwxl/docker,mixja/docker,sunyuan3/docker,gao-feng/docker,hqhq/moby,naveed-jamil-tenpearls/moby,asbjornenge/docker,vdemeester/docker,jlebon/docker,dperny/docker,moby/moby,troy0820/docker.github.io,jc-m/docker,haugene/docker,qzio/docker,Mokolea/docker,erikstmartin/docker,paralin/docker,yongtang/docker,rillig/docker.github.io,johnstep/docker.github.io,achanda/docker,jwhonce/docker,hallyn/docker,angryxlt/docker,rkazak/docker,nalind/docker,ckeyer/docker,gnailuy/docker,cyli/docker,ailispaw/docker,mike1729/docker,rhardih/docker,laijs/moby,sterchelen/docker,mrfuxi/docker,raja-sami-10p/moby,mikedanese/docker,LaynePeng/docker,geekylucas/docker,rremer/moby,vijaykilari/docker,gschaetz/moby,pragyasardana/Docker-cr-combined,ncdc/docker,docker/docker.github.io,trebonian/docker,tmp6154/docker,denverdino/denverdino.github.io,bfirsh/docker,davinashreddy/docker,Ramzec/docker,bdwill/docker.github.io,mgoelzer/docker,imkin/moby,solganik/docker,yosifkit/docker,tophj-ibm/moby,rkazak/docker,jameszhan/docker,sunyuan3/docker,denverdino/docker.github.io,PatrickLang/moby,lixiaobing10051267/docker,jlebon/docker,stainboy/docker,scollier/docker,sfsmithcha/docker,anusha-ragunathan/docker,hallyn/docker,Shopify/docker,tbonza/docker,wenchma/docker,zhangjianfnst/docker,joaofnfernandes/docker.github.io,michelvocks/docker,tbonza/docker,rhatdan/docker,msabansal/docker,Test-Betta-Inc/psychic-barnacle,jlhawn/docker,icecrime/docker,jhorwit2/docker,unclejack/docker,rremer/moby,SaiedKazemi/docker,tpounds/docker,joeuo/docker.github.io,ajaymdesai/docker,ZJUshuaizhou/docker,mahak/docker,AkihiroSuda/docker,armbuild/docker,sarnautov/moby,clintonskitson/docker,docker/docker,trebonian/docker,fsoppelsa/docker,darrenstahlmsft/docker,dongjoon-hyun/docker,jwhonce/docker,dperny/docker,contiv/docker,jzwlqx/denverdino.github.io,kunalkushwaha/docker,mgoelzer/docker,inatatsu/docker,LuisBosquez/docker.github.io,willmtemple/docker,endocode/docker,alfred-landrum/docker,djs55/docker,jthelin/docker,shhsu/docker,sreejithr/docker,gdevillele/docker.github.io,thtanaka/docker,jimjag/docker,supasate/docker,contiv/docker,harche/docker,nguyentm83/docker,jloehel/docker,noironetworks/docker,KingEmet/docker,AkihiroSuda/docker,thtanaka/docker,joeuo/docker.github.io,charleszheng44/moby,xiekeyang/docker,amatsus/docker,pyotr777/docker,HuKeping/docker,carolfh/docker,coreos/docker,rhuss/docker,JMesser81/docker,bonczj/moby-json-file-logger,anujbahuguna/docker,djs55/docker,ashmo123/docker,medallia/docker,wenchma/docker,phiroict/docker,pragyasardana/Docker-cr-combined,diogomonica/docker,tagomoris/docker,Aegeaner/docker,Mokolea/docker,davinashreddy/docker,jzwlqx/denverdino.github.io,JeffBellegarde/docker,docker/docker,Jimmy-Xu/hypercli,michelvocks/docker,s7v7nislands/docker,JimGalasyn/docker.github.io,jimjag/docker,kolyshkin/docker,mixja/docker,yasiramin10p/moby,Collinux/docker,HackToday/docker,TheBigBear/docker,jc-m/docker-medallia,gdevillele/docker.github.io,sarnautov/moby,YujiOshima/docker,tophj-ibm/docker,johnstep/moby-moby,Syntaxide/docker,hyperhq/hypercli,mauidev/docker,aidanhs/docker,thaJeztah/docker.github.io,gjaskiewicz/moby,Mokolea/docker,sdurrheimer/docker,Akasurde/docker,qudongfang/docker,jvanz/docker,JeffBellegarde/docker,kojiromike/docker,skatsuta/docker,flythecircle/gotojourney,jzwlqx/denverdino.github.io,anweiss/docker.github.io,icecrime/docker,nigelpoulton/docker,tagomoris/docker,13W/docker,arun-gupta/docker,mathewkoshy493/docker,catinthesky/docker,dnephin/docker,mikebrow/docker,sheimi/docker,ivansaracino/docker,raja-sami-10p/moby,containers/storage,aidanhs/docker,aditirajagopal/docker,charleswhchan/docker,LaynePeng/docker,JimGalasyn/docker.github.io,yummypeng/docker,cyphar/docker,ashmo123/docker,mikebrow/docker,ZJUshuaizhou/docker,aduermael/docker.github.io,aduermael/docker.github.io,shubheksha/docker.github.io,yosifkit/docker,troy0820/docker.github.io,vikstrous/docker,mkumatag/docker,aditirajagopal/docker,afein/docker,pradipd/moby,moby/moby,phiroict/docker,denverdino/denverdino.github.io,arun-gupta/docker,luxas/docker,Aegeaner/docker,zhuguihua/docker,mariusGundersen/docker,Syntaxide/docker,rancher/docker,jameszhan/docker,haveatry/docker,KarthikNayak/docker,tpounds/docker,dnephin/docker,Tenk42/docker,charleswhchan/docker,xuxinkun/docker,shishir-a412ed/docker,moypray/docker,ripcurld0/moby,kojiromike/docker,amatsus/docker,AkihiroSuda/docker,erikh/docker,nathanleclaire/docker,darrenstahlmsft/moby,docker-zh/docker.github.io,resin-io/docker,cpswan/docker,KingEmet/docker,mikedougherty/docker,Neverous/docker,KarthikNayak/docker,yummypeng/docker,endophage/docker,yp-engineering/docker,bonczj/moby-json-file-logger,dsau/docker,mtesselH/docker,willmtemple/docker,kunalkushwaha/docker,pradipd/moby,icaoweiwei/docker,cloudflare/docker,noironetworks/docker,solganik/docker,AkihiroSuda/docker,cyli/docker,upmio/docker,gigidwan/docker,stevvooe/docker,mariusGundersen/docker,mohmost12/docker,tagomoris/docker,ibuildthecloud/docker,icaoweiwei/docker,msabansal/docker,mikedougherty/docker,imeoer/hypercli,unclejack/docker,achanda/docker,prertik/docker,laijs/moby,moby/moby,qzio/docker,danix800/docker.github.io,ZJU-SEL/docker,ncdc/docker,fcrisciani/docker,tmp6154/docker,diogomonica/docker,jimjag/docker,pecameron/docker,vijaykilari/docker,izarov/docker,jvanz/docker,michael-holzheu/docker,Aegeaner/docker,sanscontext/docker.github.io,medallia/docker,shubheksha/docker.github.io,x1022as/docker,imkin/moby,Mashimiao/docker,nawawi/docker,scotttlin/docker,14rcole/docker,londoncalling/docker.github.io,kencochrane/docker,sfsmithcha/docker,anusha-ragunathan/docker,endophage/docker,pmalmgren/docker,konstruktoid/docker-1,mgoelzer/docker,nalind/docker,rhatdan/storage,BenHall/docker,nathanleclaire/docker,xiaods/docker,portworx/docker,coolljt0725/docker,swasd/baleno,ibuildthecloud/docker,BSWANG/denverdino.github.io,ffoysal/docker,Jimmy-Xu/hypercli,carolfh/docker,Ramzec/docker,ivansaracino/docker,bluebreezecf/docker,BenHall/docker,Altiscale/docker,konstruktoid/docker-upstream,menglingwei/denverdino.github.io,mike1729/docker,afein/docker,JMesser81/docker,PatrickLang/moby,twaugh/docker,whuwxl/docker,portworx/docker,michelvocks/docker,fcrisciani/docker,docker-zh/docker.github.io,cmehay/docker-1,bearstech/moby,harche/docker,moul/docker,raja-sami-10p/moby,x1022as/docker,Altiscale/docker,sterchelen/docker,ckeyer/docker,jhorwit2/docker,Test-Betta-Inc/psychic-barnacle,JimGalasyn/docker.github.io,justyntemme/docker,moypray/docker,bfirsh/docker,nghiant2710/docker,davinashreddy/docker,mrfuxi/docker,yosifkit/docker,afein/docker,pecameron/docker,madhanrm/docker,johnstep/docker.github.io,crosbymichael/docker,shishir-a412ed/docker,nghiant2710/docker,ktraghavendra/docker,xiaods/docker,luxas/docker,carolfh/docker,laijs/moby,trebonian/docker,ivansaracino/docker,maxamillion/docker,ffoysal/docker,abhinavdahiya/docker,gnailuy/docker,dsau/docker,crosbymichael/docker,paralin/docker,erikstmartin/docker,sfsmithcha/docker,geekylucas/docker,mikedougherty/docker,HuKeping/docker,cr7pt0gr4ph7/docker,johnstep/docker.github.io,haveatry/docker,jongiddy/docker,medallia/docker,ailispaw/docker,paralin/docker,denverdino/docker.github.io,izarov/docker,JMesser81/docker,cyli/docker,stainboy/docker,moxiegirl/docker,Jimmy-Xu/hypercli,madhanrm/docker,projectatomic/docker,flavio/docker,SvenDowideit/docker,xiekeyang/docker,mstanleyjones/docker,danyalKhaliq10p/moby,TrumanLing/docker,aaronlehmann/docker,gschaetz/moby,shin-/docker.github.io,zhuohual/docker,laijs/docker,tophj-ibm/moby,DoraALin/docker,konstruktoid/docker-upstream,TheBigBear/docker,dongjoon-hyun/docker,imeoer/hypercli,jameseggers/docker,londoncalling/docker.github.io,splunk/docker,flavio/docker,mssola/docker,gdevillele/docker.github.io,isubuz/docker,dgageot/docker,zelahi/docker,Morsicus/docker,bdwill/docker.github.io,rickyzhang82/docker,BSWANG/denverdino.github.io,mstanleyjones/docker,danix800/docker.github.io,mtanlee/docker,Tenk42/docker,qudongfang/docker,kyle-wang/docker,vdemeester/docker,twaugh/docker,vijaykilari/docker,docker-zh/docker.github.io,rhardih/docker,nghiant2710/docker,yangdongsheng/docker,liaoqingwei/docker,softprops/docker,jameseggers/docker,thaJeztah/docker.github.io,rhuss/docker,ndeloof/docker,mohmost12/docker,brahmaroutu/docker,naveed-jamil-tenpearls/moby,jwhonce/docker,mtanlee/docker,jthelin/docker,jecarey/docker,tklauser/docker,mbanikazemi/docker,yongtang/docker,medallia/docker,brahmaroutu/docker,jlhawn/docker,maxamillion/docker,rhatdan/storage,BrianBland/docker,skatsuta/docker,kojiromike/docker,DoraALin/docker,gigidwan/docker,srust/docker,solganik/docker,jimjag/docker,vincentwoo/docker,londoncalling/docker.github.io,erikh/docker,scotttlin/docker,swasd/baleno,q384566678/docker,dccurtis/docker,Mashimiao/docker,whuwxl/docker,dmcgowan/docker,denverdino/denverdino.github.io,charleswhchan/docker,jasonamyers/docker,zhangjianfnst/docker,lixiaobing10051267/docker,pyotr777/docker,danyalKhaliq10p/moby,liaoqingwei/docker,mahak/docker,jc-m/docker,jameszhan/docker,phiroict/docker,noxiouz/docker,mtrmac/docker,mike1729/docker,rremer/moby,moul/docker,docker/docker.github.io,sallyom/docker,13W/docker,michael-holzheu/docker,shin-/docker.github.io,wenchma/docker,cmehay/docker-1,gschaetz/moby,rhatdan/docker,kolyshkin/docker,stevvooe/docker,jongiddy/docker,dsheets/moby,JeffBellegarde/docker,coolljt0725/docker,catinthesky/docker,nawawi/docker,gnailuy/docker,LaynePeng/docker,allencloud/docker,kolyshkin/moby,luxas/docker,tklauser/docker,gdevillele/docker.github.io,noxiouz/docker,sanscontext/docker.github.io,jzwlqx/denverdino.github.io,estesp/docker,kyle-wang/docker,sdurrheimer/docker,laijs/docker,hypriot/docker,xuxinkun/docker,LuisBosquez/docker.github.io,imeoer/hypercli,fsoppelsa/docker,ZJU-SEL/docker,rillig/docker.github.io,phiroict/docker,vikstrous/docker,mahak/docker,diogomonica/docker,flythecircle/gotojourney,endocode/docker,mssola/docker,yasiramin10p/moby,nawawi/docker,thaJeztah/docker,TrumanLing/docker,danix800/docker.github.io,OnePaaS/docker,hallyn/docker,xiaods/docker,nguyentm83/docker,lixiaobing1/docker,mathewkoshy493/docker,konstruktoid/docker-upstream,naveed-jamil-tenpearls/moby,inatatsu/docker,eskaaren/docker,nigelpoulton/docker,stevvooe/docker,menglingwei/denverdino.github.io,srust/docker,abhinavdahiya/docker,dbonev/docker,erikstmartin/docker,flavio/docker,thaJeztah/docker,q384566678/docker,cmehay/docker-1,13W/docker,noxiouz/docker,tianon/docker,vdemeester/docker,dims/docker,jzwlqx/denverdino.github.io,jongiddy/docker,Distrotech/docker,ItsVeryWindy/docker,fangyuan930917/docker,coolljt0725/docker,gaobrian/docker,dperny/docker,zhuguihua/docker,skatsuta/docker,runcom/docker,cnaize/docker,cpuguy83/docker,yummypeng/docker,runcom/docker,hustcat/docker,unclejack/docker,ripcurld0/moby,cr7pt0gr4ph7/docker,ZJUshuaizhou/docker,gjaskiewicz/moby,ColinHebert/docker,sallyom/docker,Mokolea/docker,Morsicus/docker,eskaaren/docker,justyntemme/docker,ItsVeryWindy/docker,anweiss/docker.github.io,troy0820/docker.github.io,joaofnfernandes/docker.github.io,angryxlt/docker,shhsu/docker,YujiOshima/docker,ailispaw/docker,pragyasardana/Docker-cr-combined,dsau/docker,Microsoft/docker,sean-jc/docker,cnaize/docker,kimh/docker,projectatomic/docker,moxiegirl/docker,fangyuan930917/docker,Syntaxide/docker,hqhq/moby,PatrickLang/moby,sreejithr/docker,alexisbellido/docker.github.io,thaJeztah/docker.github.io,resin-io/docker,kolyshkin/moby,madhanrm/docker,gdevillele/docker.github.io,thaJeztah/docker,joeuo/docker.github.io,tophj-ibm/docker,tkopczynski/docker,coreos/docker,toli/docker,anweiss/docker.github.io,fangyuan930917/docker,hustcat/docker,umerazad/docker,denverdino/docker.github.io,asbjornenge/docker,shubheksha/docker.github.io,TheBigBear/docker,docker-zh/docker.github.io,ajneu/docker,rancher/docker,bfirsh/docker,YuPengZTE/docker,Microsoft/docker,gao-feng/docker,anortef/docker,asbjornenge/docker,rhatdan/storage,darrenstahlmsft/moby,aduermael/docker.github.io,pramodhkp/moby,dccurtis/docker,dims/docker,q384566678/docker,hypriot/docker,shin-/docker.github.io,dmcgowan/docker,jvanz/docker,mstanleyjones/docker,scollier/docker,sheimi/docker,anortef/docker,pramodhkp/moby,rillig/docker.github.io,shhsu/docker,mtanlee/docker,sanscontext/docker.github.io,eskaaren/docker,nalind/docker,darrenstahlmsft/moby,cloudflare/docker,danyalKhaliq10p/moby,ckeyer/docker,dsheets/moby,shin-/docker.github.io,miminar/docker,duglin/docker,brahmaroutu/docker,alfred-landrum/docker,danix800/docker.github.io,Altiscale/docker,KingEmet/docker,bluebreezecf/docker,resin-io/docker,softprops/docker,arun-gupta/docker,mbanikazemi/docker,mtrmac/docker,ibuildthecloud/docker,softprops/docker,j-mracek/docker,dims/docker,trebonian/docker,13W/docker,ffoysal/docker,mohmost12/docker,akira-baruah/docker,willmtemple/docker,gjaskiewicz/moby,londoncalling/docker.github.io,abhinavdahiya/docker,duglin/docker,jlebon/docker,yongtang/docker,tonistiigi/docker,ColinHebert/docker,inatatsu/docker,tmp6154/docker,gigidwan/docker,j-mracek/docker,ItsVeryWindy/docker,csfrancis/docker,rancher/docker,jloehel/docker,BenHall/docker,charleszheng44/moby,liaoqingwei/docker,xuxinkun/docker,DoraALin/docker,denverdino/denverdino.github.io,thaJeztah/docker.github.io,LuisBosquez/docker.github.io,cyphar/docker,tophj-ibm/moby,kencochrane/docker,portworx/docker,errordeveloper/docker,fcrisciani/docker,kimh/docker,kerneltime/docker,cloudflare/docker,upmio/docker,rickyzhang82/docker,swasd/baleno,Akasurde/docker,johnstep/moby-moby,docker/docker.github.io,mkumatag/docker,allencloud/docker,anujbahuguna/docker,aaronlehmann/docker,splunk/docker,kimh/docker,Tenk42/docker,denverdino/denverdino.github.io,mauidev/docker,bdwill/docker.github.io,aishraj/docker,harche/docker,kolyshkin/moby,crosbymichael/docker,runcom/docker,vincentwoo/docker,supasate/docker,Shopify/docker,HideoYamauchi/docker,menglingwei/denverdino.github.io,yp-engineering/docker,mtesselH/docker,shishir-a412ed/docker,aishraj/docker,dmcgowan/docker,alexisbellido/docker.github.io,contiv/docker,mixja/docker,sarnautov/moby,ndeloof/docker,YujiOshima/docker,isubuz/docker,moby/moby,lixiaobing1/docker,michael-holzheu/docker,tkopczynski/docker,justincormack/docker,lixiaobing10051267/docker,anweiss/docker.github.io,kerneltime/docker,fsoppelsa/docker,mariusGundersen/docker,docker/docker.github.io,tonistiigi/docker,pecameron/docker,csfrancis/docker,sallyom/docker,cpuguy83/docker,dccurtis/docker,jc-m/docker-medallia,dnephin/docker,jhorwit2/docker,YuPengZTE/docker,LuisBosquez/docker.github.io,mtesselH/docker,miminar/docker,cpswan/docker,bdwill/docker.github.io,bearstech/moby,jasonamyers/docker,Morsicus/docker,nalind/docker,hustcat/docker,mbanikazemi/docker,scotttlin/docker,Akasurde/docker,haveatry/docker