Add overlay2 description to overlayfs-driver.md
Add overlay2 description to overlayfs-driver.md

Signed-off-by: Akihiro Suda <ea940da7e429af3d0d0c18296cabd0112a36bad5@lab.ntt.co.jp>

flavio/docker,13W/docker,kunalkushwaha/docker,yongtang/docker,rhatdan/storage,prertik/docker,jwhonce/docker,mohmost12/docker,x1022as/docker,bearstech/moby,twaugh/docker,shishir-a412ed/docker,ColinHebert/docker,dmcgowan/docker,wenchma/docker,portworx/docker,thaJeztah/docker,bonczj/moby-json-file-logger,darrenstahlmsft/moby,haveatry/docker,noxiouz/docker,nalind/docker,crosbymichael/docker,prertik/docker,moypray/docker,tianon/docker,whuwxl/docker,Morsicus/docker,gnailuy/docker,splunk/docker,dims/docker,icaoweiwei/docker,AkihiroSuda/docker,lixiaobing10051267/docker,justincormack/docker,dperny/docker,coreos/docker,jhorwit2/docker,coolljt0725/docker,mtesselH/docker,darrenstahlmsft/moby,SvenDowideit/docker,hqhq/moby,kojiromike/docker,bearstech/moby,alfred-landrum/docker,moby/moby,tmp6154/docker,tkopczynski/docker,jlhawn/docker,crosbymichael/docker,stevvooe/docker,mkumatag/docker,sdurrheimer/docker,justyntemme/docker,dnephin/docker,yosifkit/docker,noironetworks/docker,michelvocks/docker,jameszhan/docker,paralin/docker,gjaskiewicz/moby,mtrmac/docker,pradipd/moby,PatrickLang/moby,thaJeztah/docker,konstruktoid/docker-upstream,moypray/docker,srust/docker,shishir-a412ed/docker,xuxinkun/docker,estesp/docker,eskaaren/docker,asbjornenge/docker,mahak/docker,Morsicus/docker,mstanleyjones/docker,diogomonica/docker,rhatdan/docker,harche/docker,wenchma/docker,amatsus/docker,rremer/moby,tophj-ibm/docker,maxamillion/docker,darrenstahlmsft/moby,alfred-landrum/docker,KingEmet/docker,srust/docker,bluebreezecf/docker,pradipd/moby,unclejack/docker,xiaods/docker,miminar/docker,splunk/docker,johnstep/moby-moby,mixja/docker,AkihiroSuda/docker,mikebrow/docker,yasiramin10p/moby,dccurtis/docker,ajaymdesai/docker,brahmaroutu/docker,lixiaobing10051267/docker,konstruktoid/docker-upstream,Syntaxide/docker,cr7pt0gr4ph7/docker,pramodhkp/moby,coreos/docker,sarnautov/moby,mikedougherty/docker,paralin/docker,cpuguy83/docker,yosifkit/docker,kunalkushwaha/docker,kunalkushwaha/docker,mtanlee/docker,trebonian/docker,Ramzec/docker,dsheets/moby,dims/docker,eskaaren/docker,jthelin/docker,naveed-jamil-tenpearls/moby,diogomonica/docker,moby/moby,xiaods/docker,x1022as/docker,jlebon/docker,noxiouz/docker,yummypeng/docker,sfsmithcha/docker,gnailuy/docker,yp-engineering/docker,yummypeng/docker,tagomoris/docker,paralin/docker,moby/moby,msabansal/docker,jlebon/docker,akira-baruah/docker,sanjeo/docker,PatrickLang/moby,yongtang/docker,tklauser/docker,kencochrane/docker,thaJeztah/docker,zhuguihua/docker,moby/moby,lixiaobing10051267/docker,liaoqingwei/docker,KingEmet/docker,fcrisciani/docker,fcrisciani/docker,sanjeo/docker,AkihiroSuda/docker,shhsu/docker,brahmaroutu/docker,duglin/docker,bonczj/moby-json-file-logger,jimjag/docker,jameszhan/docker,ffoysal/docker,pramodhkp/moby,Mokolea/docker,kolyshkin/moby,yp-engineering/docker,rancher/docker,miminar/docker,HideoYamauchi/docker,stevvooe/docker,liaoqingwei/docker,qudongfang/docker,dperny/docker,gjaskiewicz/moby,sterchelen/docker,gschaetz/moby,allencloud/docker,bearstech/moby,erikstmartin/docker,mohmost12/docker,POLJM242/docker,Ramzec/docker,catinthesky/docker,brahmaroutu/docker,shhsu/docker,ndeloof/docker,ndeloof/docker,scotttlin/docker,asbjornenge/docker,mkumatag/docker,afein/docker,kolyshkin/moby,charleszheng44/moby,KarthikNayak/docker,portworx/docker,KingEmet/docker,harche/docker,bonczj/moby-json-file-logger,trebonian/docker,xuxinkun/docker,haveatry/docker,AkihiroSuda/docker,kencochrane/docker,sterchelen/docker,mixja/docker,imkin/moby,moul/docker,abhinavdahiya/docker,raja-sami-10p/moby,kojiromike/docker,madhanrm/docker,jlhawn/docker,mahak/docker,hypriot/docker,HuKeping/docker,noironetworks/docker,resin-io/docker,mkumatag/docker,PatrickLang/moby,mtesselH/docker,mixja/docker,konstruktoid/docker-upstream,harche/docker,ibuildthecloud/docker,resin-io/docker,JMesser81/docker,imkin/moby,kolyshkin/docker,yp-engineering/docker,kencochrane/docker,hqhq/moby,laijs/moby,lixiaobing1/docker,HideoYamauchi/docker,sfsmithcha/docker,thtanaka/docker,djs55/docker,xiekeyang/docker,ibuildthecloud/docker,bearstech/moby,moul/docker,charleszheng44/moby,q384566678/docker,sdurrheimer/docker,moul/docker,afein/docker,laijs/docker,laijs/docker,flavio/docker,SvenDowideit/docker,michelvocks/docker,moul/docker,hqhq/moby,POLJM242/docker,Ramzec/docker,mstanleyjones/docker,nalind/docker,Mokolea/docker,endophage/docker,SvenDowideit/docker,dgageot/docker,mtesselH/docker,cpuguy83/docker,dnephin/docker,KarthikNayak/docker,jhorwit2/docker,icaoweiwei/docker,maxamillion/docker,allencloud/docker,nawawi/docker,nalind/docker,cloudflare/docker,x1022as/docker,ibuildthecloud/docker,jimjag/docker,tonistiigi/docker,dsheets/moby,rhatdan/storage,HuKeping/docker,docker/docker,jimjag/docker,laijs/moby,mikedougherty/docker,pramodhkp/moby,sfsmithcha/docker,q384566678/docker,michael-holzheu/docker,gnailuy/docker,gschaetz/moby,duglin/docker,raja-sami-10p/moby,estesp/docker,afein/docker,fcrisciani/docker,tophj-ibm/docker,ColinHebert/docker,qudongfang/docker,zhuguihua/docker,jvanz/docker,coolljt0725/docker,ffoysal/docker,noironetworks/docker,dmcgowan/docker,xiekeyang/docker,gschaetz/moby,naveed-jamil-tenpearls/moby,Morsicus/docker,erikh/docker,vdemeester/docker,trebonian/docker,raja-sami-10p/moby,mahak/docker,dnephin/docker,dsau/docker,cyphar/docker,madhanrm/docker,tklauser/docker,dims/docker,jlhawn/docker,catinthesky/docker,xuxinkun/docker,Syntaxide/docker,xiekeyang/docker,jlebon/docker,dsau/docker,justyntemme/docker,nawawi/docker,KarthikNayak/docker,splunk/docker,flavio/docker,q384566678/docker,JMesser81/docker,jthelin/docker,rhatdan/docker,mike1729/docker,rremer/moby,michael-holzheu/docker,gnailuy/docker,darrenstahlmsft/docker,containers/storage,scotttlin/docker,mike1729/docker,cr7pt0gr4ph7/docker,dsau/docker,duglin/docker,dongjoon-hyun/docker,gjaskiewicz/moby,dongjoon-hyun/docker,nawawi/docker,mikebrow/docker,abhinavdahiya/docker,danyalKhaliq10p/moby,projectatomic/docker,dgageot/docker,miminar/docker,nawawi/docker,rhatdan/storage,amatsus/docker,tophj-ibm/moby,YuPengZTE/docker,xiaods/docker,13W/docker,Syntaxide/docker,mtrmac/docker,unclejack/docker,wenchma/docker,kolyshkin/docker,coreos/docker,yasiramin10p/moby,cpuguy83/docker,kolyshkin/moby,jvanz/docker,msabansal/docker,haveatry/docker,dgageot/docker,unclejack/docker,ColinHebert/docker,mstanleyjones/docker,mikebrow/docker,estesp/docker,mikedougherty/docker,jvanz/docker,13W/docker,jameszhan/docker,jhorwit2/docker,paralin/docker,noxiouz/docker,dmcgowan/docker,konstruktoid/docker-upstream,tophj-ibm/moby,shhsu/docker,icaoweiwei/docker,stevvooe/docker,ibuildthecloud/docker,darrenstahlmsft/docker,sarnautov/moby,ibuildthecloud/docker,naveed-jamil-tenpearls/moby,cloudflare/docker,laijs/docker,mahak/docker,13W/docker,ajaymdesai/docker,shishir-a412ed/docker,johnstep/moby-moby,allencloud/docker,YuPengZTE/docker,cyphar/docker,jwhonce/docker,thtanaka/docker,tophj-ibm/docker,dccurtis/docker,scotttlin/docker,tonistiigi/docker,dsheets/moby,yongtang/docker,hypriot/docker,dperny/docker,ndeloof/docker,JMesser81/docker,diogomonica/docker,michael-holzheu/docker,YuPengZTE/docker,qudongfang/docker,tmp6154/docker,prertik/docker,mohmost12/docker,madhanrm/docker,mike1729/docker,docker/docker,konstruktoid/docker-1,erikstmartin/docker,hypriot/docker,projectatomic/docker,jwhonce/docker,laijs/moby,erikh/docker,rancher/docker,sanjeo/docker,sarnautov/moby,erikh/docker,cyphar/docker,rhatdan/docker,resin-io/docker,tkopczynski/docker,charleszheng44/moby,justincormack/docker,mtanlee/docker,maxamillion/docker,sdurrheimer/docker,docker/docker,konstruktoid/docker-1,bluebreezecf/docker,HideoYamauchi/docker,ripcurld0/moby,lixiaobing1/docker,twaugh/docker,cloudflare/docker,tkopczynski/docker,Ramzec/docker,tagomoris/docker,dccurtis/docker,liaoqingwei/docker,michelvocks/docker,tagomoris/docker,akira-baruah/docker,nalind/docker,ajaymdesai/docker,imkin/moby,justincormack/docker,containers/storage,cpuguy83/docker,trebonian/docker,yosifkit/docker,projectatomic/docker,mtanlee/docker,dongjoon-hyun/docker,tmp6154/docker,portworx/docker,tklauser/docker,mtrmac/docker,djs55/docker,vdemeester/docker,danyalKhaliq10p/moby,jimjag/docker,amatsus/docker,twaugh/docker,crosbymichael/docker,thtanaka/docker,vdemeester/docker,darrenstahlmsft/docker,cr7pt0gr4ph7/docker,endophage/docker,abhinavdahiya/docker,bluebreezecf/docker,whuwxl/docker,erikstmartin/docker,msabansal/docker,Mokolea/docker,moypray/docker,asbjornenge/docker,lixiaobing1/docker,tophj-ibm/moby,13W/docker,rancher/docker,thaJeztah/docker,djs55/docker,konstruktoid/docker-1,coolljt0725/docker,flavio/docker,tianon/docker,tonistiigi/docker,endophage/docker,pradipd/moby,HuKeping/docker,zhuguihua/docker,ripcurld0/moby,srust/docker,Mokolea/docker,kojiromike/docker,rremer/moby,catinthesky/docker,yasiramin10p/moby,yummypeng/docker,sterchelen/docker,containers/storage,johnstep/moby-moby,ffoysal/docker,whuwxl/docker,yosifkit/docker,ripcurld0/moby,alfred-landrum/docker,justyntemme/docker,eskaaren/docker,danyalKhaliq10p/moby