docs/extend/plugins.md: add docker-volume-ploop
docs/extend/plugins.md: add docker-volume-ploop

Added docker-volume-ploop driver to the list of available volume plugins.

Signed-off-by: Kir Kolyshkin <c0159612b0ef32139322233232df1a0d189c4b9b@openvz.org>
shubheksha/docker.github.io,michael-holzheu/docker,amatsus/docker,JMesser81/docker,scotttlin/docker,michael-holzheu/docker,cpuguy83/docker,aduermael/docker.github.io,kunalkushwaha/docker,jlebon/docker,thaJeztah/docker.github.io,gdevillele/docker.github.io,ndeloof/docker,dgageot/docker,tophj-ibm/docker,coreos/docker,Syntaxide/docker,rhatdan/docker,johnstep/docker.github.io,Mokolea/docker,michelvocks/docker,tklauser/docker,whuwxl/docker,endophage/docker,docker/docker.github.io,anweiss/docker.github.io,bearstech/moby,bdwill/docker.github.io,trebonian/docker,sarnautov/moby,coreos/docker,dsau/docker,LuisBosquez/docker.github.io,lixiaobing10051267/docker,jongiddy/docker,sanscontext/docker.github.io,bdwill/docker.github.io,phiroict/docker,Mokolea/docker,mtanlee/docker,dnephin/docker,alexisbellido/docker.github.io,darrenstahlmsft/moby,rillig/docker.github.io,laijs/docker,dongjoon-hyun/docker,pecameron/docker,mixja/docker,HideoYamauchi/docker,moul/docker,medallia/docker,duglin/docker,moby/moby,icaoweiwei/docker,sfsmithcha/docker,stainboy/docker,rhatdan/storage,yongtang/docker,kunalkushwaha/docker,KingEmet/docker,stevvooe/docker,maxamillion/docker,laijs/moby,yasiramin10p/moby,docker-zh/docker.github.io,q384566678/docker,pramodhkp/moby,bluebreezecf/docker,dsheets/moby,johnstep/moby-moby,prertik/docker,cr7pt0gr4ph7/docker,kojiromike/docker,madhanrm/docker,icaoweiwei/docker,gschaetz/moby,msabansal/docker,gnailuy/docker,gdevillele/docker.github.io,mahak/docker,docker/docker,abhinavdahiya/docker,dperny/docker,gdevillele/docker.github.io,yosifkit/docker,lixiaobing10051267/docker,afein/docker,cyphar/docker,HuKeping/docker,danyalKhaliq10p/moby,dccurtis/docker,Shopify/docker,kolyshkin/moby,unclejack/docker,whuwxl/docker,jzwlqx/denverdino.github.io,darrenstahlmsft/moby,rremer/moby,denverdino/denverdino.github.io,mkumatag/docker,nawawi/docker,SvenDowideit/docker,hqhq/moby,dgageot/docker,kolyshkin/docker,justyntemme/docker,dmcgowan/docker,jimjag/docker,eskaaren/docker,brahmaroutu/docker,nawawi/docker,amatsus/docker,noxiouz/docker,djs55/docker,sanscontext/docker.github.io,jvanz/docker,hypriot/docker,stevvooe/docker,yp-engineering/docker,ibuildthecloud/docker,dmcgowan/docker,BSWANG/denverdino.github.io,laijs/docker,Morsicus/docker,HideoYamauchi/docker,nghiant2710/docker,shishir-a412ed/docker,kolyshkin/moby,dperny/docker,alexisbellido/docker.github.io,vdemeester/docker,trebonian/docker,naveed-jamil-tenpearls/moby,maxamillion/docker,menglingwei/denverdino.github.io,ripcurld0/moby,unclejack/docker,trebonian/docker,joaofnfernandes/docker.github.io,YuPengZTE/docker,lixiaobing1/docker,cyphar/docker,mstanleyjones/docker,splunk/docker,pecameron/docker,medallia/docker,gdevillele/docker.github.io,Ramzec/docker,eskaaren/docker,nghiant2710/docker,mohmost12/docker,jthelin/docker,dongjoon-hyun/docker,LuisBosquez/docker.github.io,jlebon/docker,dsau/docker,joeuo/docker.github.io,YuPengZTE/docker,coolljt0725/docker,coreos/docker,gnailuy/docker,x1022as/docker,kojiromike/docker,darrenstahlmsft/moby,tophj-ibm/moby,sanjeo/docker,sarnautov/moby,cpuguy83/docker,Shopify/docker,BSWANG/denverdino.github.io,phiroict/docker,cloudflare/docker,msabansal/docker,AkihiroSuda/docker,charleszheng44/moby,troy0820/docker.github.io,denverdino/docker.github.io,mgoelzer/docker,yosifkit/docker,yp-engineering/docker,aduermael/docker.github.io,twaugh/docker,laijs/docker,charleswhchan/docker,haveatry/docker,kunalkushwaha/docker,pradipd/moby,noironetworks/docker,13W/docker,BSWANG/denverdino.github.io,YuPengZTE/docker,allencloud/docker,danyalKhaliq10p/moby,dperny/docker,mikebrow/docker,moul/docker,tophj-ibm/docker,yp-engineering/docker,imkin/moby,ColinHebert/docker,KarthikNayak/docker,bearstech/moby,x1022as/docker,mikedougherty/docker,docker-zh/docker.github.io,justincormack/docker,nalind/docker,moby/moby,dnephin/docker,Syntaxide/docker,afein/docker,rremer/moby,ajaymdesai/docker,xiaods/docker,mtanlee/docker,JMesser81/docker,catinthesky/docker,allencloud/docker,mtrmac/docker,sanscontext/docker.github.io,liaoqingwei/docker,kencochrane/docker,justyntemme/docker,pramodhkp/moby,13W/docker,mixja/docker,anweiss/docker.github.io,joeuo/docker.github.io,KingEmet/docker,paralin/docker,kencochrane/docker,scotttlin/docker,erikstmartin/docker,jameszhan/docker,bluebreezecf/docker,jhorwit2/docker,johnstep/docker.github.io,kencochrane/docker,brahmaroutu/docker,medallia/docker,sfsmithcha/docker,shhsu/docker,moul/docker,asbjornenge/docker,anweiss/docker.github.io,crosbymichael/docker,akira-baruah/docker,nalind/docker,djs55/docker,sanscontext/docker.github.io,jlebon/docker,JimGalasyn/docker.github.io,PatrickLang/moby,sanscontext/docker.github.io,mikebrow/docker,crosbymichael/docker,shin-/docker.github.io,mkumatag/docker,sfsmithcha/docker,justincormack/docker,tonistiigi/docker,shubheksha/docker.github.io,ffoysal/docker,trebonian/docker,diogomonica/docker,ColinHebert/docker,x1022as/docker,asbjornenge/docker,gnailuy/docker,yummypeng/docker,ibuildthecloud/docker,thtanaka/docker,dmcgowan/docker,gjaskiewicz/moby,ajaymdesai/docker,thaJeztah/docker,docker-zh/docker.github.io,13W/docker,POLJM242/docker,haveatry/docker,prertik/docker,abhinavdahiya/docker,endophage/docker,ibuildthecloud/docker,dsheets/moby,haveatry/docker,rhatdan/docker,londoncalling/docker.github.io,imkin/moby,joaofnfernandes/docker.github.io,noironetworks/docker,jongiddy/docker,afein/docker,wenchma/docker,phiroict/docker,denverdino/denverdino.github.io,docker/docker.github.io,sanjeo/docker,flavio/docker,bdwill/docker.github.io,unclejack/docker,pradipd/moby,danyalKhaliq10p/moby,yosifkit/docker,cpuguy83/docker,tagomoris/docker,joeuo/docker.github.io,konstruktoid/docker-1,yosifkit/docker,cr7pt0gr4ph7/docker,docker/docker,yasiramin10p/moby,tonistiigi/docker,PatrickLang/moby,fcrisciani/docker,shubheksha/docker.github.io,jzwlqx/denverdino.github.io,joaofnfernandes/docker.github.io,miminar/docker,Mokolea/docker,jthelin/docker,akira-baruah/docker,AkihiroSuda/docker,moul/docker,shin-/docker.github.io,hypriot/docker,vdemeester/docker,ndeloof/docker,twaugh/docker,shhsu/docker,catinthesky/docker,gnailuy/docker,justyntemme/docker,jimjag/docker,thtanaka/docker,cpuguy83/docker,wenchma/docker,SvenDowideit/docker,mikedougherty/docker,flavio/docker,justincormack/docker,flavio/docker,mohmost12/docker,jameszhan/docker,moby/moby,rhatdan/docker,thaJeztah/docker.github.io,erikstmartin/docker,thtanaka/docker,moypray/docker,liaoqingwei/docker,BSWANG/denverdino.github.io,madhanrm/docker,stainboy/docker,tmp6154/docker,thaJeztah/docker,dongjoon-hyun/docker,thaJeztah/docker.github.io,joaofnfernandes/docker.github.io,laijs/moby,srust/docker,paralin/docker,rhatdan/storage,mstanleyjones/docker,splunk/docker,abhinavdahiya/docker,phiroict/docker,xiaods/docker,whuwxl/docker,xiekeyang/docker,jzwlqx/denverdino.github.io,harche/docker,projectatomic/docker,denverdino/denverdino.github.io,LuisBosquez/docker.github.io,bonczj/moby-json-file-logger,imkin/moby,estesp/docker,resin-io/docker,johnstep/moby-moby,bearstech/moby,jlhawn/docker,fcrisciani/docker,shhsu/docker,alexisbellido/docker.github.io,mixja/docker,bonczj/moby-json-file-logger,dims/docker,docker-zh/docker.github.io,mikedougherty/docker,docker/docker.github.io,diogomonica/docker,containers/storage,cloudflare/docker,mgoelzer/docker,flavio/docker,londoncalling/docker.github.io,jzwlqx/denverdino.github.io,menglingwei/denverdino.github.io,asbjornenge/docker,zhuguihua/docker,madhanrm/docker,nawawi/docker,yongtang/docker,troy0820/docker.github.io,tagomoris/docker,dgageot/docker,Morsicus/docker,xuxinkun/docker,qudongfang/docker,joeuo/docker.github.io,danix800/docker.github.io,tophj-ibm/docker,projectatomic/docker,shin-/docker.github.io,troy0820/docker.github.io,JMesser81/docker,londoncalling/docker.github.io,naveed-jamil-tenpearls/moby,JimGalasyn/docker.github.io,jvanz/docker,icaoweiwei/docker,HideoYamauchi/docker,konstruktoid/docker-upstream,dsheets/moby,JimGalasyn/docker.github.io,denverdino/denverdino.github.io,gschaetz/moby,tophj-ibm/moby,jimjag/docker,gjaskiewicz/moby,mikebrow/docker,mahak/docker,londoncalling/docker.github.io,jwhonce/docker,stevvooe/docker,zhuguihua/docker,konstruktoid/docker-upstream,estesp/docker,jongiddy/docker,sdurrheimer/docker,medallia/docker,AkihiroSuda/docker,ffoysal/docker,srust/docker,KingEmet/docker,darrenstahlmsft/docker,anweiss/docker.github.io,charleszheng44/moby,pramodhkp/moby,noxiouz/docker,menglingwei/denverdino.github.io,erikh/docker,raja-sami-10p/moby,jzwlqx/denverdino.github.io,rancher/docker,mtesselH/docker,konstruktoid/docker-1,portworx/docker,danix800/docker.github.io,projectatomic/docker,hqhq/moby,resin-io/docker,hypriot/docker,ndeloof/docker,srust/docker,bdwill/docker.github.io,sdurrheimer/docker,thaJeztah/docker.github.io,shin-/docker.github.io,POLJM242/docker,ajaymdesai/docker,tianon/docker,mahak/docker,HuKeping/docker,xuxinkun/docker,bonczj/moby-json-file-logger,mahak/docker,sdurrheimer/docker,rancher/docker,ripcurld0/moby,docker/docker.github.io,maxamillion/docker,jameszhan/docker,tklauser/docker,q384566678/docker,alfred-landrum/docker,bearstech/moby,hqhq/moby,mtesselH/docker,Syntaxide/docker,portworx/docker,docker-zh/docker.github.io,sterchelen/docker,aduermael/docker.github.io,JimGalasyn/docker.github.io,xiekeyang/docker,jvanz/docker,anweiss/docker.github.io,yongtang/docker,mike1729/docker,raja-sami-10p/moby,londoncalling/docker.github.io,tkopczynski/docker,duglin/docker,noxiouz/docker,tagomoris/docker,joaofnfernandes/docker.github.io,13W/docker,containers/storage,zhuguihua/docker,denverdino/docker.github.io,13W/docker,estesp/docker,charleswhchan/docker,danix800/docker.github.io,jlhawn/docker,PatrickLang/moby,docker/docker,amatsus/docker,ColinHebert/docker,jhorwit2/docker,johnstep/docker.github.io,dims/docker,mike1729/docker,duglin/docker,konstruktoid/docker-upstream,shubheksha/docker.github.io,KarthikNayak/docker,gjaskiewicz/moby,gschaetz/moby,resin-io/docker,xuxinkun/docker,coolljt0725/docker,thaJeztah/docker.github.io,tianon/docker,lixiaobing1/docker,stainboy/docker,AkihiroSuda/docker,johnstep/docker.github.io,pradipd/moby,sanjeo/docker,allencloud/docker,johnstep/docker.github.io,JimGalasyn/docker.github.io,darrenstahlmsft/docker,rhatdan/storage,sterchelen/docker,wenchma/docker,coolljt0725/docker,menglingwei/denverdino.github.io,nalind/docker,KarthikNayak/docker,ripcurld0/moby,shishir-a412ed/docker,jwhonce/docker,Morsicus/docker,SvenDowideit/docker,liaoqingwei/docker,denverdino/docker.github.io,denverdino/docker.github.io,lixiaobing1/docker,konstruktoid/docker-1,containers/storage,dnephin/docker,rillig/docker.github.io,jimjag/docker,dsau/docker,qudongfang/docker,rillig/docker.github.io,xiaods/docker,crosbymichael/docker,bdwill/docker.github.io,paralin/docker,LuisBosquez/docker.github.io,mstanleyjones/docker,catinthesky/docker,dims/docker,nawawi/docker,Shopify/docker,ffoysal/docker,q384566678/docker,pecameron/docker,ibuildthecloud/docker,LuisBosquez/docker.github.io,shubheksha/docker.github.io,yasiramin10p/moby,erikstmartin/docker,joeuo/docker.github.io,sterchelen/docker,mkumatag/docker,tmp6154/docker,alexisbellido/docker.github.io,danix800/docker.github.io,kolyshkin/docker,shishir-a412ed/docker,jhorwit2/docker,cr7pt0gr4ph7/docker,jlhawn/docker,cloudflare/docker,xiekeyang/docker,djs55/docker,miminar/docker,cyphar/docker,erikh/docker,prertik/docker,paralin/docker,sarnautov/moby,kolyshkin/moby,miminar/docker,fcrisciani/docker,moypray/docker,rancher/docker,tonistiigi/docker,jwhonce/docker,tmp6154/docker,dccurtis/docker,scotttlin/docker,mgoelzer/docker,docker/docker.github.io,michelvocks/docker,endophage/docker,HuKeping/docker,mtanlee/docker,BSWANG/denverdino.github.io,noironetworks/docker,harche/docker,mohmost12/docker,portworx/docker,twaugh/docker,charleswhchan/docker,nalind/docker,rillig/docker.github.io,alfred-landrum/docker,tkopczynski/docker,mtrmac/docker,menglingwei/denverdino.github.io,yummypeng/docker,aduermael/docker.github.io,msabansal/docker,darrenstahlmsft/docker,harche/docker,konstruktoid/docker-upstream,charleszheng44/moby,splunk/docker,diogomonica/docker,denverdino/denverdino.github.io,tklauser/docker,eskaaren/docker,laijs/moby,thaJeztah/docker,mtrmac/docker,alexisbellido/docker.github.io,dccurtis/docker,johnstep/moby-moby,troy0820/docker.github.io,moypray/docker,mtesselH/docker,michael-holzheu/docker,Ramzec/docker,alfred-landrum/docker,bluebreezecf/docker,shin-/docker.github.io,naveed-jamil-tenpearls/moby,mike1729/docker,phiroict/docker,thaJeztah/docker,vdemeester/docker,nghiant2710/docker,Ramzec/docker,raja-sami-10p/moby,erikh/docker,lixiaobing10051267/docker,yummypeng/docker,ibuildthecloud/docker,kojiromike/docker,qudongfang/docker,denverdino/docker.github.io,tophj-ibm/moby,moby/moby,michelvocks/docker,Mokolea/docker,gdevillele/docker.github.io,tkopczynski/docker,rremer/moby,brahmaroutu/docker,Ramzec/docker