CONTRIBUTING: add guidelines regarding email
CONTRIBUTING: add guidelines regarding email

This adds guidelines around reaching the maintainers. Emails shouldn't
be sent to maintainers. GitHub mentions should be used instead.

Signed-off-by: Cristian Staretu <78db8d24f2e00709fded2f6f25e9a572f4b7462f@gmail.com>

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