add system hooks api docs to help content
add system hooks api docs to help content

Razer6/gitlabhq,pkallberg/tjenare,kotaro-dev/gitlab-6-9,MauriceMohlek/gitlabhq,Keystion/gitlabhq,pkallberg/tjenare,johnmyqin/gitlabhq,sue445/gitlabhq,zBMNForks/gitlabhq,initiummedia/gitlabhq,johnmyqin/gitlabhq,chenrui2014/gitlabhq,ferdinandrosario/gitlabhq,nguyen-tien-mulodo/gitlabhq,tk23/gitlabhq,chenrui2014/gitlabhq,jrjang/gitlab-ce,michaKFromParis/sparkslab,williamherry/gitlabhq,since2014/gitlabhq,shinexiao/gitlabhq,LUMC/gitlabhq,akumetsuv/gitlab,lbt/gitlabhq,fearenales/gitlabhq,iiet/iiet-git,jairzh/gitlabhq-sfdc,ayufan/gitlabhq,manfer/gitlabhq,it33/gitlabhq,atomaka/gitlabhq,8thcolor/eurucamp2014-htdsadr,revaret/gitlabhq,hq804116393/gitlabhq,tempbottle/gitlabhq,delkyd/gitlabhq,cui-liqiang/gitlab-ce,youprofit/gitlabhq,windymid/test2,ksoichiro/gitlabhq,mmkassem/gitlabhq,sue445/gitlabhq,rhels/gitlabhq,Tyrael/gitlabhq,gopeter/gitlabhq,liyakun/gitlabhq,yatish27/gitlabhq,jairzh/gitlabhq-sfdc,sakishum/gitlabhq,gopeter/gitlabhq,ngpestelos/gitlabhq,gorgee/gitlabhq,yulchitaj/TEST3,michaKFromParis/sparkslab,iiet/iiet-git,salipro4ever/gitlabhq,TheWatcher/gitlabhq,windymid/test2,rfeese/gitlab-ce,atomaka/gitlabhq,since2014/gitlabhq,aaronsnyder/gitlabhq,shinexiao/gitlabhq,screenpages/gitlabhq,8thcolor/rubyconfau2015-sadr,jrjang/gitlab-ce,ttasanen/gitlabhq,fendoudeqingchunhh/gitlabhq,Burick/gitlabhq,LytayTOUCH/gitlabhq,gorgee/gitlabhq,kotaro-dev/gitlab-6-9,jrjang/gitlabhq,SkyWei/gitlabhq,ordiychen/gitlabhq,it33/gitlabhq,per-garden/gitlabhq,julianengel/gitlabhq,bladealslayer/gitlabhq,jirutka/gitlabhq,Keystion/gitlabhq,joalmeid/gitlabhq,zrbsprite/gitlabhq,Datacom/gitlabhq,revaret/gitlabhq,Devin001/gitlabhq,fgbreel/gitlabhq,luzhongyang/gitlabhq,stoplightio/gitlabhq,lvfeng1130/gitlabhq,Burick/gitlabhq,martinma4/gitlabhq,chadyred/gitlabhq,Razer6/gitlabhq,jrjang/gitlabhq,zBMNForks/gitlabhq,bbodenmiller/gitlabhq,ferdinandrosario/gitlabhq,mr-dxdy/gitlabhq,axilleas/gitlabhq,manfer/gitlabhq,shinexiao/gitlabhq,LytayTOUCH/gitlabhq,yama07/gitlabhq,adaiguoguo/gitlab_globalserarch,dukex/gitlabhq,t-zuehlsdorff/gitlabhq,jaepyoung/gitlabhq,rfeese/gitlab-ce,H3Chief/gitlabhq,nguyen-tien-mulodo/gitlabhq,atomaka/gitlabhq,pjknkda/gitlabhq,cinderblock/gitlabhq,achako/gitlabhq,rebecamendez/gitlabhq,dvrylc/gitlabhq,Kambda/Mobbr,tempbottle/gitlabhq,nmav/gitlabhq,koreamic/gitlabhq,Burick/gitlabhq,fantasywind/gitlabhq,OlegGirko/gitlab-ce,cui-liqiang/gitlab-ce,dukex/gitlabhq,wangcan2014/gitlabhq,mavimo/gitlabhq,NARKOZ/gitlabhq,Soullivaneuh/gitlabhq,mr-dxdy/gitlabhq,louahola/gitlabhq,dplarson/gitlabhq,Kambda/mobbr-gitlabhq,flashbuckets/gitlabhq,Datacom/gitlabhq,bbodenmiller/gitlabhq,stoplightio/gitlabhq,fantasywind/gitlabhq,Kambda/mobbr-gitlabhq,fearenales/gitlabhq,tk23/gitlabhq,shinexiao/gitlabhq,axilleas/gitlabhq,achako/gitlabhq,revaret/gitlabhq,wangcan2014/gitlabhq,mathstuf/gitlabhq,adaiguoguo/gitlab_globalserarch,theodi/gitlabhq,nmav/gitlabhq,dwrensha/gitlabhq,sonalkr132/gitlabhq,vjustov/gitlabhq,ferdinandrosario/gitlabhq,sue445/gitlabhq,NuLL3rr0r/gitlabhq,Datacom/gitlabhq,zBMNForks/gitlabhq,whluwit/gitlabhq,openwide-java/gitlabhq,initiummedia/gitlabhq,mavimo/gitlabhq,yonglehou/gitlabhq,stanhu/gitlabhq,larryli/gitlabhq,lbt/gitlabhq,sonalkr132/gitlabhq,TheWatcher/gitlabhq,theonlydoo/gitlabhq,dwrensha/gitlabhq,t-zuehlsdorff/gitlabhq,fearenales/gitlabhq,cinderblock/gitlabhq,larryli/gitlabhq,ikappas/gitlabhq,LUMC/gitlabhq,NARKOZ/gitlabhq,H3Chief/gitlabhq,rumpelsepp/gitlabhq,initiummedia/gitlabhq,1ed/gitlabhq,jvanbaarsen/gitlabhq,daiyu/gitlab-zh,bozaro/gitlabhq,fpgentil/gitlabhq,8thcolor/testing-public-gitlabhq,fscherwi/gitlabhq,ordiychen/gitlabhq,Exeia/gitlabhq,hzy001/gitlabhq,stellamiranda/mobbr-gitlabhq,pulkit21/gitlabhq,revaret/gitlabhq,sonalkr132/gitlabhq,Keystion/gitlabhq,rebecamendez/gitlabhq,tk23/gitlabhq,jrjang/gitlab-ce,dplarson/gitlabhq,mente/gitlabhq,8thcolor/eurucamp2014-htdsadr,nguyen-tien-mulodo/gitlabhq,zBMNForks/gitlabhq,tempbottle/gitlabhq,cui-liqiang/gitlab-ce,wangcan2014/gitlabhq,daiyu/gitlab-zh,vjustov/gitlabhq,ordiychen/gitlabhq,hzy001/gitlabhq,allysonbarros/gitlabhq,NuLL3rr0r/gitlabhq,0x20h/gitlabhq,kemenaran/gitlabhq,lvfeng1130/gitlabhq,jirutka/gitlabhq,mavimo/gitlabhq,ZeoAlliance/gitlabhq,dwrensha/gitlabhq,chenrui2014/gitlabhq,duduribeiro/gitlabhq,mrb/gitlabhq,kitech/gitlabhq,SVArago/gitlabhq,neiljbrookes/glab,allysonbarros/gitlabhq,fendoudeqingchunhh/gitlabhq,pupaxxo/gitlabhq,pulkit21/gitlabhq,H3Chief/gitlabhq,k4zzk/gitlabhq,yfaizal/gitlabhq,michaKFromParis/sparkslab,mathstuf/gitlabhq,0x20h/gitlabhq,OtkurBiz/gitlabhq,Datacom/gitlabhq,michaKFromParis/gitlabhq,Telekom-PD/gitlabhq,sekcheong/gitlabhq,SVArago/gitlabhq,gorgee/gitlabhq,martinma4/gitlabhq,rumpelsepp/gitlabhq,stanhu/gitlabhq,ibiart/gitlabhq,gopeter/gitlabhq,sakishum/gitlabhq,dukex/gitlabhq,kemenaran/gitlabhq,bigsurge/gitlabhq,folpindo/gitlabhq,childbamboo/gitlabhq,sideci-sample/sideci-sample-gitlabhq,CodeCantor/gitlabhq,8thcolor/eurucamp2014-htdsadr,123Haynes/gitlabhq,dplarson/gitlabhq,screenpages/gitlabhq,MauriceMohlek/gitlabhq,LytayTOUCH/gitlabhq,betabot7/gitlabhq,whluwit/gitlabhq,flashbuckets/gitlabhq,mathstuf/gitlabhq,martinma4/gitlabhq,rhels/gitlabhq,bozaro/gitlabhq,szechyjs/gitlabhq,michaKFromParis/gitlabhq,larryli/gitlabhq,Devin001/gitlabhq,cinderblock/gitlabhq,allistera/gitlabhq,bigsurge/gitlabhq,yama07/gitlabhq,TheWatcher/gitlabhq,hacsoc/gitlabhq,nmav/gitlabhq,kemenaran/gitlabhq,DanielZhangQingLong/gitlabhq,tim-hoff/gitlabhq,LytayTOUCH/gitlabhq,bozaro/gitlabhq,wangcan2014/gitlabhq,dukex/gitlabhq,jaepyoung/gitlabhq,allysonbarros/gitlabhq,adaiguoguo/gitlab_globalserarch,michaKFromParis/gitlabhqold,koreamic/gitlabhq,ikappas/gitlabhq,tim-hoff/gitlabhq,fgbreel/gitlabhq,cncodog/gitlab,theodi/gitlabhq,mr-dxdy/gitlabhq,martijnvermaat/gitlabhq,yonglehou/gitlabhq,yonglehou/gitlabhq,yatish27/gitlabhq,michaKFromParis/gitlabhqold,adaiguoguo/gitlab_globalserarch,julianengel/gitlabhq,joalmeid/gitlabhq,hacsoc/gitlabhq,ArthurHoaro/Public-GitLab,CodeCantor/gitlabhq,bozaro/gitlabhq,fgbreel/gitlabhq,folpindo/gitlabhq,joalmeid/gitlabhq,cncodog/gitlab,icedwater/gitlabhq,ngpestelos/gitlabhq,screenpages/gitlabhq,lbt/gitlabhq,8thcolor/testing-public-gitlabhq,yama07/gitlabhq,since2014/gitlabhq,jvanbaarsen/gitlabhq,koreamic/gitlabhq,martinma4/gitlabhq,SVArago/gitlabhq,eliasp/gitlabhq,ngpestelos/gitlabhq,phinfonet/mobbr-gitlabhq,axilleas/gitlabhq,SVArago/gitlabhq,ZeoAlliance/gitlabhq,folpindo/gitlabhq,jrjang/gitlabhq,icedwater/gitlabhq,goeun/myRepo,pkallberg/tjenare,jaepyoung/gitlabhq,WSDC-NITWarangal/gitlabhq,t-zuehlsdorff/gitlabhq,ZeoAlliance/gitlabhq,pupaxxo/gitlabhq,htve/GitlabForChinese,flashbuckets/gitlabhq,copystudy/gitlabhq,allysonbarros/gitlabhq,SkyWei/gitlabhq,dreampet/gitlab,salipro4ever/gitlabhq,mathstuf/gitlabhq,yulchitaj/TEST3,salipro4ever/gitlabhq,daiyu/gitlab-zh,cncodog/gitlab,jrjang/gitlabhq,iiet/iiet-git,fscherwi/gitlabhq,yulchitaj/TEST3,yama07/gitlabhq,fantasywind/gitlabhq,WSDC-NITWarangal/gitlabhq,aaronsnyder/gitlabhq,fpgentil/gitlabhq,openwide-java/gitlabhq,hq804116393/gitlabhq,MauriceMohlek/gitlabhq,theodi/gitlabhq,yatish27/gitlabhq,joalmeid/gitlabhq,eliasp/gitlabhq,rumpelsepp/gitlabhq,mmkassem/gitlabhq,bigsurge/gitlabhq,cui-liqiang/gitlab-ce,cinderblock/gitlabhq,0x20h/gitlabhq,xuvw/gitlabhq,achako/gitlabhq,jirutka/gitlabhq,larryli/gitlabhq,michaKFromParis/gitlabhq,SkyWei/gitlabhq,lvfeng1130/gitlabhq,darkrasid/gitlabhq,iiet/iiet-git,per-garden/gitlabhq,Telekom-PD/gitlabhq,darkrasid/gitlabhq,ttasanen/gitlabhq,theonlydoo/gitlabhq,betabot7/gitlabhq,williamherry/gitlabhq,chenrui2014/gitlabhq,jairzh/gitlabhq-sfdc,delkyd/gitlabhq,Soullivaneuh/gitlabhq,yfaizal/gitlabhq,williamherry/gitlabhq,eliasp/gitlabhq,mente/gitlabhq,darkrasid/gitlabhq,delkyd/gitlabhq,stoplightio/gitlabhq,sue445/gitlabhq,fendoudeqingchunhh/gitlabhq,OlegGirko/gitlab-ce,yatish27/gitlabhq,NKMR6194/gitlabhq,darkrasid/gitlabhq,hzy001/gitlabhq,Kambda/Mobbr,youprofit/gitlabhq,neiljbrookes/glab,ArthurHoaro/Public-GitLab,manfer/gitlabhq,ksoichiro/gitlabhq,sakishum/gitlabhq,8thcolor/testing-public-gitlabhq,ngpestelos/gitlabhq,neiljbrookes/glab,akumetsuv/gitlab,hq804116393/gitlabhq,rfeese/gitlab-ce,Soullivaneuh/gitlabhq,yuyue2013/ss,duduribeiro/gitlabhq,openwide-java/gitlabhq,louahola/gitlabhq,123Haynes/gitlabhq,hzy001/gitlabhq,Razer6/gitlabhq,mrb/gitlabhq,k4zzk/gitlabhq,since2014/gitlabhq,dvrylc/gitlabhq,martijnvermaat/gitlabhq,kitech/gitlabhq,Exeia/gitlabhq,tim-hoff/gitlabhq,phinfonet/mobbr-gitlabhq,NARKOZ/gitlabhq,WSDC-NITWarangal/gitlabhq,OtkurBiz/gitlabhq,icedwater/gitlabhq,Burick/gitlabhq,mrb/gitlabhq,MauriceMohlek/gitlabhq,pupaxxo/gitlabhq,copystudy/gitlabhq,childbamboo/gitlabhq,bladealslayer/gitlabhq,bbodenmiller/gitlabhq,DanielZhangQingLong/gitlabhq,8thcolor/rubyconfau2015-sadr,hacsoc/gitlabhq,johnmyqin/gitlabhq,Tyrael/gitlabhq,jrjang/gitlab-ce,rebecamendez/gitlabhq,fpgentil/gitlabhq,ayufan/gitlabhq,sakishum/gitlabhq,DanielZhangQingLong/gitlabhq,nguyen-tien-mulodo/gitlabhq,kemenaran/gitlabhq,xuvw/gitlabhq,DanielZhangQingLong/gitlabhq,stanhu/gitlabhq,Exeia/gitlabhq,ikappas/gitlabhq,pkgr/gitlabhq,per-garden/gitlabhq,ArthurHoaro/Public-GitLab,hq804116393/gitlabhq,htve/GitlabForChinese,stoplightio/gitlabhq,daiyu/gitlab-zh,goeun/myRepo,Razer6/gitlabhq,martijnvermaat/gitlabhq,dreampet/gitlab,yuyue2013/ss,sekcheong/gitlabhq,lvfeng1130/gitlabhq,vjustov/gitlabhq,WSDC-NITWarangal/gitlabhq,mente/gitlabhq,youprofit/gitlabhq,mavimo/gitlabhq,pkgr/gitlabhq,8thcolor/rubyconfau2015-sadr,k4zzk/gitlabhq,rumpelsepp/gitlabhq,pulkit21/gitlabhq,pjknkda/gitlabhq,1ed/gitlabhq,duduribeiro/gitlabhq,jirutka/gitlabhq,zrbsprite/gitlabhq,ksoichiro/gitlabhq,123Haynes/gitlabhq,jvanbaarsen/gitlabhq,duduribeiro/gitlabhq,yuyue2013/ss,yfaizal/gitlabhq,mente/gitlabhq,dvrylc/gitlabhq,openwide-java/gitlabhq,dreampet/gitlab,dvrylc/gitlabhq,icedwater/gitlabhq,yfaizal/gitlabhq,Telekom-PD/gitlabhq,vjustov/gitlabhq,per-garden/gitlabhq,initiummedia/gitlabhq,fendoudeqingchunhh/gitlabhq,rhels/gitlabhq,Keystion/gitlabhq,nmav/gitlabhq,windymid/test2,fgbreel/gitlabhq,szechyjs/gitlabhq,Tyrael/gitlabhq,aaronsnyder/gitlabhq,ibiart/gitlabhq,xuvw/gitlabhq,julianengel/gitlabhq,jaepyoung/gitlabhq,pkgr/gitlabhq,dwrensha/gitlabhq,martijnvermaat/gitlabhq,chadyred/gitlabhq,ordiychen/gitlabhq,SkyWei/gitlabhq,stellamiranda/mobbr-gitlabhq,liyakun/gitlabhq,it33/gitlabhq,dreampet/gitlab,liyakun/gitlabhq,whluwit/gitlabhq,pjknkda/gitlabhq,stellamiranda/mobbr-gitlabhq,childbamboo/gitlabhq,gopeter/gitlabhq,OtkurBiz/gitlabhq,LUMC/gitlabhq,NuLL3rr0r/gitlabhq,eliasp/gitlabhq,jairzh/gitlabhq-sfdc,H3Chief/gitlabhq,NKMR6194/gitlabhq,folpindo/gitlabhq,sideci-sample/sideci-sample-gitlabhq,jvanbaarsen/gitlabhq,theodi/gitlabhq,k4zzk/gitlabhq,ibiart/gitlabhq,allistera/gitlabhq,childbamboo/gitlabhq,gorgee/gitlabhq,michaKFromParis/gitlabhqold,1ed/gitlabhq,sekcheong/gitlabhq,michaKFromParis/gitlabhqold,akumetsuv/gitlab,CodeCantor/gitlabhq,mr-dxdy/gitlabhq,stanhu/gitlabhq,ikappas/gitlabhq,Exeia/gitlabhq,OlegGirko/gitlab-ce,luzhongyang/gitlabhq,bladealslayer/gitlabhq,Devin001/gitlabhq,ttasanen/gitlabhq,copystudy/gitlabhq,hacsoc/gitlabhq,yulchitaj/TEST3,michaKFromParis/gitlabhq,szechyjs/gitlabhq,yuyue2013/ss,fantasywind/gitlabhq,theonlydoo/gitlabhq,fscherwi/gitlabhq,TheWatcher/gitlabhq,ayufan/gitlabhq,betabot7/gitlabhq,fpgentil/gitlabhq,goeun/myRepo,htve/GitlabForChinese,Kambda/mobbr-gitlabhq,louahola/gitlabhq,luzhongyang/gitlabhq,rhels/gitlabhq,youprofit/gitlabhq,dplarson/gitlabhq,luzhongyang/gitlabhq,pjknkda/gitlabhq,screenpages/gitlabhq,koreamic/gitlabhq,Tyrael/gitlabhq,szechyjs/gitlabhq,sekcheong/gitlabhq,Telekom-PD/gitlabhq,pulkit21/gitlabhq,copystudy/gitlabhq,NKMR6194/gitlabhq,LUMC/gitlabhq,rfeese/gitlab-ce,OtkurBiz/gitlabhq,ferdinandrosario/gitlabhq,ayufan/gitlabhq,ttasanen/gitlabhq,louahola/gitlabhq,mmkassem/gitlabhq,it33/gitlabhq,aaronsnyder/gitlabhq,rebecamendez/gitlabhq,NARKOZ/gitlabhq,delkyd/gitlabhq,zrbsprite/gitlabhq,Kambda/Mobbr,bbodenmiller/gitlabhq,tk23/gitlabhq,zrbsprite/gitlabhq,theonlydoo/gitlabhq,yonglehou/gitlabhq,cncodog/gitlab,williamherry/gitlabhq,kotaro-dev/gitlab-6-9,kitech/gitlabhq,chadyred/gitlabhq,htve/GitlabForChinese,ksoichiro/gitlabhq,fearenales/gitlabhq,michaKFromParis/sparkslab,phinfonet/mobbr-gitlabhq,johnmyqin/gitlabhq,allistera/gitlabhq,Devin001/gitlabhq,Soullivaneuh/gitlabhq,axilleas/gitlabhq,mrb/gitlabhq,whluwit/gitlabhq,NKMR6194/gitlabhq,bigsurge/gitlabhq,sideci-sample/sideci-sample-gitlabhq,salipro4ever/gitlabhq,liyakun/gitlabhq,chadyred/gitlabhq,mmkassem/gitlabhq,kitech/gitlabhq,manfer/gitlabhq,tim-hoff/gitlabhq,allistera/gitlabhq,tempbottle/gitlabhq,fscherwi/gitlabhq,OlegGirko/gitlab-ce,t-zuehlsdorff/gitlabhq,julianengel/gitlabhq,sonalkr132/gitlabhq,flashbuckets/gitlabhq