Add zsh completion for 'docker system df'
Add zsh completion for 'docker system df'

Signed-off-by: Steve Durrheimer <a2c1a055e5b399822be341b4e663de3cd05cf8f7@gmail.com>

yosifkit/docker,diogomonica/docker,JMesser81/docker,bearstech/moby,estesp/docker,q384566678/docker,dccurtis/docker,mkumatag/docker,paralin/docker,yasiramin10p/moby,mixja/docker,jimjag/docker,estesp/docker,johnstep/moby-moby,liaoqingwei/docker,mtesselH/docker,darrenstahlmsft/moby,nalind/docker,danyalKhaliq10p/moby,thaJeztah/docker,yongtang/docker,srust/docker,crosbymichael/docker,pradipd/moby,yosifkit/docker,sdurrheimer/docker,erikstmartin/docker,PatrickLang/moby,dgageot/docker,sterchelen/docker,dims/docker,justincormack/docker,mikebrow/docker,vdemeester/docker,coreos/docker,kencochrane/docker,mkumatag/docker,laijs/docker,tmp6154/docker,mike1729/docker,Ramzec/docker,kencochrane/docker,tianon/docker,darrenstahlmsft/moby,naveed-jamil-tenpearls/moby,liaoqingwei/docker,mikedougherty/docker,moul/docker,docker/docker,sterchelen/docker,thtanaka/docker,mtrmac/docker,mtesselH/docker,maxamillion/docker,AkihiroSuda/docker,djs55/docker,haveatry/docker,vdemeester/docker,trebonian/docker,sarnautov/moby,harche/docker,gschaetz/moby,erikh/docker,tophj-ibm/docker,prertik/docker,cyphar/docker,amatsus/docker,mikedougherty/docker,danyalKhaliq10p/moby,yummypeng/docker,dims/docker,gjaskiewicz/moby,fcrisciani/docker,scotttlin/docker,bonczj/moby-json-file-logger,amatsus/docker,trebonian/docker,tophj-ibm/moby,djs55/docker,Mokolea/docker,mstanleyjones/docker,resin-io/docker,jimjag/docker,ripcurld0/moby,jimjag/docker,tonistiigi/docker,bearstech/moby,haveatry/docker,mikebrow/docker,KingEmet/docker,tophj-ibm/moby,kolyshkin/moby,miminar/docker,ffoysal/docker,konstruktoid/docker-upstream,laijs/moby,jimjag/docker,duglin/docker,raja-sami-10p/moby,duglin/docker,HideoYamauchi/docker,tianon/docker,vdemeester/docker,flavio/docker,ColinHebert/docker,lixiaobing10051267/docker,dmcgowan/docker,lixiaobing1/docker,ripcurld0/moby,ibuildthecloud/docker,Syntaxide/docker,nawawi/docker,erikh/docker,sarnautov/moby,flavio/docker,jvanz/docker,cpuguy83/docker,gschaetz/moby,laijs/docker,mahak/docker,HideoYamauchi/docker,trebonian/docker,yongtang/docker,YuPengZTE/docker,yosifkit/docker,diogomonica/docker,mixja/docker,scotttlin/docker,ndeloof/docker,konstruktoid/docker-1,resin-io/docker,KingEmet/docker,fcrisciani/docker,djs55/docker,kojiromike/docker,tophj-ibm/docker,flavio/docker,dperny/docker,ffoysal/docker,jthelin/docker,laijs/docker,tonistiigi/docker,gjaskiewicz/moby,haveatry/docker,moul/docker,shishir-a412ed/docker,SvenDowideit/docker,YuPengZTE/docker,ffoysal/docker,thtanaka/docker,ColinHebert/docker,kencochrane/docker,imkin/moby,liaoqingwei/docker,thaJeztah/docker,madhanrm/docker,pramodhkp/moby,q384566678/docker,mahak/docker,jwhonce/docker,konstruktoid/docker-1,KarthikNayak/docker,unclejack/docker,ndeloof/docker,erikstmartin/docker,michael-holzheu/docker,JMesser81/docker,ColinHebert/docker,erikstmartin/docker,qudongfang/docker,dsheets/moby,akira-baruah/docker,thtanaka/docker,tklauser/docker,tophj-ibm/docker,kojiromike/docker,fcrisciani/docker,darrenstahlmsft/docker,xuxinkun/docker,rhatdan/docker,dgageot/docker,x1022as/docker,konstruktoid/docker-upstream,bearstech/moby,jlhawn/docker,AkihiroSuda/docker,docker/docker,Mokolea/docker,trebonian/docker,unclejack/docker,jwhonce/docker,gnailuy/docker,danyalKhaliq10p/moby,dgageot/docker,xuxinkun/docker,darrenstahlmsft/moby,catinthesky/docker,gnailuy/docker,unclejack/docker,raja-sami-10p/moby,mkumatag/docker,scotttlin/docker,tklauser/docker,YuPengZTE/docker,konstruktoid/docker-upstream,gnailuy/docker,moypray/docker,alfred-landrum/docker,cyphar/docker,konstruktoid/docker-upstream,whuwxl/docker,mike1729/docker,diogomonica/docker,crosbymichael/docker,allencloud/docker,moypray/docker,hqhq/moby,shhsu/docker,gschaetz/moby,coreos/docker,Syntaxide/docker,mikebrow/docker,jwhonce/docker,pradipd/moby,laijs/moby,mahak/docker,nawawi/docker,prertik/docker,Syntaxide/docker,yongtang/docker,qudongfang/docker,yosifkit/docker,tmp6154/docker,imkin/moby,moby/moby,imkin/moby,estesp/docker,mtesselH/docker,nawawi/docker,tmp6154/docker,docker/docker,yummypeng/docker,paralin/docker,whuwxl/docker,ibuildthecloud/docker,stevvooe/docker,jlhawn/docker,AkihiroSuda/docker,pramodhkp/moby,madhanrm/docker,resin-io/docker,dccurtis/docker,ibuildthecloud/docker,rremer/moby,dims/docker,stevvooe/docker,dmcgowan/docker,thaJeztah/docker,ndeloof/docker,lixiaobing1/docker,KarthikNayak/docker,kolyshkin/docker,mike1729/docker,hqhq/moby,shhsu/docker,michael-holzheu/docker,moul/docker,miminar/docker,qudongfang/docker,thaJeztah/docker,maxamillion/docker,lixiaobing10051267/docker,pramodhkp/moby,x1022as/docker,gnailuy/docker,rancher/docker,sterchelen/docker,POLJM242/docker,jthelin/docker,alfred-landrum/docker,jameszhan/docker,Ramzec/docker,yummypeng/docker,catinthesky/docker,johnstep/moby-moby,KarthikNayak/docker,mtrmac/docker,yasiramin10p/moby,noironetworks/docker,KingEmet/docker,yasiramin10p/moby,jameszhan/docker,miminar/docker,noironetworks/docker,raja-sami-10p/moby,duglin/docker,mtrmac/docker,dperny/docker,rancher/docker,coolljt0725/docker,dperny/docker,dccurtis/do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