doc: Mention contributor agreement immediately after Gerrit
doc: Mention contributor agreement immediately after Gerrit

I walked through the steps for a contribution but ended up
with an error when doing "git mail" because I didn't have a
signed agreement.

Added a section to check for or create one through Gerrit right
after the user has created the account and logged in.

Moved some info from copyright section to the new section.

Change-Id: I79bbd3e18fc3a742fa59a242085da14be9e19ba0
Reviewed-on: https://go-review.googlesource.com/13062
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

AALEKH/go,miolini/go,monetate/go,JioCloud/go,ifagnosticism/go,alex-zhang/go,devpadawan/go,xiuzhifu/go,vsekhar/elastic-go,jmptrader/go,josharian/go,wangfakang/go-1,dterei/go,suncycheng/go,chinanjjohn2012/go,WIZARD-CXY/go,vsdutka/go,JioCloud/go,stormltf/go,rachtsingh/gogojuice,willjunspecial/go,zouchao2010/go,yangzhongj/go,fjballest/golang,sosop/go,miolini/go,constantine001/go,ObjectiveJoe/go,theass/go,josharian/go,nawawi/go,Badredapple/go,yuhengye/go,alex-zhang/go,dpatel06/go,dafyddcrosby/go,samanalysis/go,4ad/go,codestation/go,kakuhiroshi/go,myPublicGit/go,donnel6809/go,famorted/go,polyverse-security/go,alash3al/go,Young55555/go,jacobxk/go,goodlang/good,dpatel06/go,undergrowthlinear/go,rentongzhang/go,parkdy/go,mikekap/go,ganboing/go-esx,GeorgiCodes/go,zcwfeng/go,famorted/go,goodlang/good,ErikDubbelboer/go,danielsoro/go,CAFxX/go,andrewchambers/go,akutz/go,ericsnowcurrently/go,mbrukman/go,jonahglover/go,Stan-Lin-/go,theif519/go,alex-zhang/go,Young55555/go,vishsingh/go,binarycrusader/go,samanalysis/go,josharian/go,danycoro/go,slavau/go,deft-code/go,josharian/go,rachtsingh/gogojuice,famorted/go,ericsnowcurrently/go,leeric92/go,xujianhai/go,vishsingh/go,JioCloud/go,jacobhaven/go,Badredapple/go,lihuanghai/go,Charlesdong/go-1,chinanjjohn2012/go,beealone/go,shines77/go,CAFxX/go,vishsingh/go,jacobxk/go,golang/go,CiscoCloud/go,ericsnowcurrently/go,uileyar/go,jacobsa/go,Jordanzuo/go,jonahglover/go,theif519/go,CAFxX/go,CodyGuo/go,golang/go,xujianhai/go,joshsammut/go,NunoEdgarGub1/go,WIZARD-CXY/go,derekmarcotte/go,Charlesdong/go-1,nakedgc/go,slavau/go,CarterTsai/go,gdey/go,xiaobodu/go,jasonxiong/go,arschles/golang-go,theass/go,mbrukman/go,cainiaocome/go,myPublicGit/go,uileyar/go,goodlang/good,theass/go,gdey/go,XuYunnan/go,zouchao2010/go,ObjectiveJoe/go,honsiorovskyi/go,cainiaocome/go,jefby/go,Stan-Lin-/go,rentongzhang/go,malvira/go,arschles/golang-go,yuhengye/go,xiaobodu/go,malvira/go,ichu501/go,ObjectiveJoe/go,jasonxiong/go,jdhenke/go,jonathanmarvens/go,XuYunnan/go,momchil-velikov/go,sosop/go,kim-racktop/go,jacobhaven/go,ErikDubbelboer/go,odeke-em/go,WIZARD-CXY/go,dterei/go,Badredapple/go,arschles/golang-go,jdhenke/go,skotti/go,springning/go,zouchao2010/go,albertjin/golang-go,joshsammut/go,kevinc0825/go,cookerzhu/go,CarterTsai/go,g522342435/go,cookerzhu/go,yasarkunduz/go,ImJasonH/go,sosop/go,fjballest/golang,josharian/go,rentongzhang/go,monetate/go,gdey/go,Endika/go,CodyGuo/go,GeorgiCodes/go,famorted/go,vsdutka/go,roth1002/go,rentongzhang/go,fjballest/golang,vsekhar/elastic-go,g522342435/go,golang/go,lihuanghai/go,springning/go,slavau/go,deft-code/go,deft-code/go,shines77/go,jdeng/go,sndnvaps/go,vsdutka/go,likesea/go,joshsammut/go,theass/go,springning/go,alex-zhang/go,honsiorovskyi/go,mbrukman/go,mdp/go,devpadawan/go,mwhudson/go,devpadawan/go,CiscoCloud/go,snowsnail/go,xiaobodu/go,suncycheng/go,jonasi/go,zcwfeng/go,monetate/go,mikekap/go,willjunspecial/go,theass/go,donnel6809/go,greyhwndz/go,malvira/go,skotti/go,Cofyc/go,stormltf/go,dafyddcrosby/go,mgyenik/go,polyverse-security/go,kim-racktop/go,Badredapple/go,Samurais/go,mdp/go,mwhudson/go,samanalysis/go,wangfakang/go-1,dafyddcrosby/go,leeric92/go,kevinc0825/go,goodlang/good,fjballest/golang,wangfakang/go-1,jasonxiong/go,Jordanzuo/go,skatsuta/go,yuhengye/go,b54898533/go,b54898533/go,yangzhongj/go,mikekap/go,cookerzhu/go,jacobxk/go,Cofyc/go,nakedgc/go,devpadawan/go,ganboing/go-esx,mikekap/go,alash3al/go,donnel6809/go,jmptrader/go,jdeng/go,parkdy/go,snowsnail/go,jasonxiong/go,jefby/go,likesea/go,xiaobodu/go,odeke-em/go,dpatel06/go,rachtsingh/gogojuice,CodyGuo/go,ifagnosticism/go,rachtsingh/gogojuice,jdhenke/go,albertjin/golang-go,b54898533/go,vsdutka/go,xujianhai/go,stormltf/go,alex-zhang/go,Badredapple/go,CiscoCloud/go,snowsnail/go,kim-racktop/go,skatsuta/go,constantine001/go,jonathanmarvens/go,ImJasonH/go,AALEKH/go,jdeng/go,dpatel06/go,jefby/go,theif519/go,polyverse-security/go,Pulgafree/go,jonathanmarvens/go,golang/go,Jordanzuo/go,shines77/go,joshsammut/go,ErikDubbelboer/go,codestation/go,cyberroadie/go,jdeng/go,springning/go,xujianhai/go,dafyddcrosby/go,ImJasonH/go,joshsammut/go,mgyenik/go,skotti/go,willjunspecial/go,Jordanzuo/go,fjballest/golang,ichu501/go,sndnvaps/go,vsekhar/elastic-go,Pulgafree/go,devpadawan/go,mbrukman/go,cookerzhu/go,akutz/go,likesea/go,binarycrusader/go,yasarkunduz/go,lihuanghai/go,sinuos/go,mdp/go,sosop/go,Samurais/go,christopher-henderson/Go,vanloswang/go,ganboing/go-esx,theass/go,g522342435/go,ImJasonH/go,Pulgafree/go,vsdutka/go,vsdutka/go,Pulgafree/go,vanloswang/go,mwhudson/go,jonasi/go,b54898533/go,zcwfeng/go,mbrukman/go,mgyenik/go,vishsingh/go,sosop/go,myPublicGit/go,mgyenik/go,donnel6809/go,Pulgafree/go,vishsingh/go,stormltf/go,arschles/go-1,ifagnosticism/go,chinanjjohn2012/go,xiuzhifu/go,gdey/go,sinuos/go,greyhwndz/go,jacobxk/go,goodlang/good,mikekap/go,miolini/go,mdp/go,dpatel06/go,devpadawan/go,XuYunnan/go,mgyenik/go,JioCloud/go,4ad/go,suncycheng/go,xiuzhifu/go,polyverse-security/go,jameskumar/go,AALEKH/go,cloudflare/go,g522342435/go,jacobsa/go,dafyddcrosby/go,Jordanzuo/go,jacobhaven/go,Stan-Lin-/go,Stan-Lin-/go,golang/go,b54898533/go,miolini/go,AALEKH/go,albertjin/golang-go,constantine001/go,sinuos/go,binarycrusader/go,mwhudson/go,mgyenik/go,linux-on-ibm-z/go,andrewchambers/go,goodlang/good,fjballest/golang,yasarkunduz/go,binarycrusader/go,linux-on-ibm-z/go,jacobsa/go,sosop/go,kevinc0825/go,dpatel06/go,jonahglover/go,sndnvaps/go,derekmarcotte/go,willjunspecial/go,danielsoro/go,lihuanghai/go,deft-code/go,parkdy/go,jonasi/go,alash3al/go,wangfakang/go-1,josharian/go,danielsoro/go,monetate/go,cyberroadie/go,ericsnowcurrently/go,jdeng/go,undergrowthlinear/go,Pulgafree/go,arschles/go-1,CiscoCloud/go,kevinc0825/go,alash3al/go,ifagnosticism/go,ganboing/go-esx,momchil-velikov/go,Samurais/go,greyhwndz/go,danielsoro/go,derekmarcotte/go,chinanjjohn2012/go,willjunspecial/go,akutz/go,jacobxk/go,miolini/go,linux-on-ibm-z/go,XuYunnan/go,b54898533/go,gdey/go,sndnvaps/go,cainiaocome/go,CarterTsai/go,famorted/go,jameskumar/go,zhangg/go,nakedgc/go,zhangg/go,odeke-em/go,Samurais/go,skatsuta/go,kevinc0825/go,rachtsingh/gogojuice,likesea/go,akutz/go,Charlesdong/go-1,xiuzhifu/go,derekmarcotte/go,springning/go,yuhengye/go,zouchao2010/go,NichoZhang/go,Jordanzuo/go,greyhwndz/go,CarterTsai/go,gdey/go,goodlang/good,skatsuta/go,sndnvaps/go,kakuhiroshi/go,xiaobodu/go,jacobxk/go,jacobhaven/go,jacobsa/go,monetate/go,skotti/go,snowsnail/go,GeorgiCodes/go,wangfakang/go-1,nawawi/go,sinuos/go,ichu501/go,binarycrusader/go,vanloswang/go,XuYunnan/go,roth1002/go,honsiorovskyi/go,codestation/go,cainiaocome/go,alash3al/go,parkdy/go,qskycolor/go,mwhudson/go,suncycheng/go,binarycrusader/go,willjunspecial/go,danielsoro/go,Charlesdong/go-1,jacobxk/go,sinuos/go,Cofyc/go,zcwfeng/go,jefby/go,yangzhongj/go,mdp/go,zcwfeng/go,vanloswang/go,constantine001/go,CodyGuo/go,arschles/golang-go,greyhwndz/go,jefby/go,XuYunnan/go,CodyGuo/go,linux-on-ibm-z/go,alash3al/go,NichoZhang/go,jonasi/go,nawawi/go,ifagnosticism/go,NichoZhang/go,ObjectiveJoe/go,NunoEdgarGub1/go,Endika/go,cloudflare/go,golang/go,binarycrusader/go,ichu501/go,lihuanghai/go,rachtsingh/gogojuice,CAFxX/go,rachtsingh/gogojuice,stormltf/go,NunoEdgarGub1/go,dafyddcrosby/go,Stan-Lin-/go,jdeng/go,snowsnail/go,jacobsa/go,danielsoro/go,jameskumar/go,polyverse-security/go,jonahglover/go,linux-on-ibm-z/go,mikekap/go,rentongzhang/go,arschles/go-1,jonathanmarvens/go,ObjectiveJoe/go,jacobhaven/go,g522342435/go,ericsnowcurrently/go,slavau/go,snowsnail/go,jonahglover/go,yuhengye/go,zhangg/go,vsekhar/elastic-go,momchil-velikov/go,WIZARD-CXY/go,cyberroadie/go,sosop/go,ObjectiveJoe/go,jonathanmarvens/go,Pulgafree/go,Charlesdong/go-1,qskycolor/go,akutz/go,zouchao2010/go,jonasi/go,danycoro/go,donnel6809/go,xujianhai/go,CAFxX/go,myPublicGit/go,jdeng/go,skotti/go,mdp/go,jmptrader/go,samanalysis/go,jonahglover/go,codestation/go,GeorgiCodes/go,zouchao2010/go,danycoro/go,ericsnowcurrently/go,derekmarcotte/go,Endika/go,jdhenke/go,4ad/go,g522342435/go,Young55555/go,beealone/go,deft-code/go,rachtsingh/gogojuice,yasarkunduz/go,CiscoCloud/go,greyhwndz/go,sndnvaps/go,sinuos/go,codestation/go,cloudflare/go,cyberroadie/go,suncycheng/go,JioCloud/go,Samurais/go,jameskumar/go,CarterTsai/go,ganboing/go-esx,4ad/go,arschles/golang-go,Young55555/go,slavau/go,odeke-em/go,zhangg/go,b54898533/go,leeric92/go,ImJasonH/go,binarycrusader/go,malvira/go,nawawi/go,mwhudson/go,vsekhar/elastic-go,nakedgc/go,kevinc0825/go,kakuhiroshi/go,myPublicGit/go,albertjin/golang-go,deft-code/go,jdhenke/go,cyberroadie/go,danycoro/go,leeric92/go,gdey/go,ImJasonH/go,shines77/go,ericsnowcurrently/go,jmptrader/go,beealone/go,jonathanmarvens/go,kim-racktop/go,zhangg/go,albertjin/golang-go,greyhwndz/go,andrewchambers/go,WIZARD-CXY/go,4ad/go,odeke-em/go,NichoZhang/go,sosop/go,theif519/go,Samurais/go,NichoZhang/go,vishsingh/go,danycoro/go,mikekap/go,snowsnail/go,Stan-Lin-/go,theif519/go,vanloswang/go,WIZARD-CXY/go,goodlang/good,jonasi/go,likesea/go,jacobhaven/go,ErikDubbelboer/go,ericsnowcurrently/go,vsdutka/go,jacobsa/go,chinanjjohn2012/go,nakedgc/go,fjballest/golang,linux-on-ibm-z/go,4ad/go,dterei/go,AALEKH/go,jmptrader/go,yuhengye/go,kakuhiroshi/go,Young55555/go,likesea/go,slavau/go,skotti/go,josharian/go,nakedgc/go,nawawi/go,Endika/go,skotti/go,cyberroadie/go,yangzhongj/go,cainiaocome/go,Endika/go,jacobsa/go,wangfakang/go-1,alex-zhang/go,beealone/go,stormltf/go,yangzhongj/go,mbrukman/go,dpatel06/go,myPublicGit/go,fjballest/golang,ganboing/go-esx,donnel6809/go,jacobsa/go,beealone/go,xiuzhifu/go,codestation/go,parkdy/go,joshsammut/go,devpadawan/go,Samurais/go,b54898533/go,NichoZhang/go,uileyar/go,kim-racktop/go,Cofyc/go,vanloswang/go,cookerzhu/go,Young55555/go,jdhenke/go,yasarkunduz/go,slavau/go,dterei/go,CarterTsai/go,honsiorovskyi/go,sndnvaps/go,slavau/go,GeorgiCodes/go,dpatel06/go,jacobxk/go,polyverse-security/go,Badredapple/go,arschles/go-1,andrewchambers/go,yasarkunduz/go,AALEKH/go,nawawi/go,jmptrader/go,theass/go,beealone/go,odeke-em/go,akutz/go,Endika/go,WIZARD-CXY/go,willjunspecial/go,kim-racktop/go,yasarkunduz/go,theif519/go,likesea/go,springning/go,andrewchambers/go,xiaobodu/go,vsekhar/elastic-go,Charlesdong/go-1,devpadawan/go,Cofyc/go,likesea/go,myPublicGit/go,shines77/go,NunoEdgarGub1/go,mbrukman/go,jameskumar/go,golang/go,ErikDubbelboer/go,danycoro/go,NichoZhang/go,ichu501/go,chinanjjohn2012/go,deft-code/go,xiuzhifu/go,nakedgc/go,jefby/go,zouchao2010/go,ObjectiveJoe/go,lihuanghai/go,momchil-velikov/go,donnel6809/go,mdp/go,samanalysis/go,chinanjjohn2012/go,CodyGuo/go,qskycolor/go,miolini/go,WIZARD-CXY/go,cainiaocome/go,NunoEdgarGub1/go,jefby/go,malvira/go,springning/go,miolini/go,xiuzhifu/go,Charlesdong/go-1,jacobhaven/go,skatsuta/go,zouchao2010/go,roth1002/go,suncycheng/go,mgyenik/go,honsiorovskyi/go,dterei/go,cookerzhu/go,mikekap/go,JioCloud/go,mbrukman/go,momchil-velikov/go,cloudflare/go,suncycheng/go,jasonxiong/go,ImJasonH/go,qskycolor/go,codestation/go,alash3al/go,cloudflare/go,jasonxiong/go,joshsammut/go,kim-racktop/go,deft-code/go,andrewchambers/go,cloudflare/go,rentongzhang/go,derekmarcotte/go,golang/go,stormltf/go,zhangg/go,yasarkunduz/go,ifagnosticism/go,malvira/go,polyverse-security/go,momchil-velikov/go,Pulgafree/go,wangfakang/go-1,jdhenke/go,codestation/go,ichu501/go,stormltf/go,danielsoro/go,zhangg/go,GeorgiCodes/go,Jordanzuo/go,nakedgc/go,polyverse-security/go,CAFxX/go,vanloswang/go,4ad/go,shines77/go,skatsuta/go,Young55555/go,akutz/go,Stan-Lin-/go,Charlesdong/go-1,danycoro/go,CiscoCloud/go,derekmarcotte/go,alash3al/go,qskycolor/go,zhangg/go,linux-on-ibm-z/go,CarterTsai/go,ImJasonH/go,monetate/go,jonasi/go,Jordanzuo/go,jameskumar/go,jasonxiong/go,cyberroadie/go,undergrowthlinear/go,samanalysis/go,gdey/go,nawawi/go,mwhudson/go,roth1002/go,honsiorovskyi/go,undergrowthlinear/go,mgyenik/go,constantine001/go,vsekhar/elastic-go,theass/go,undergrowthlinear/go,kevinc0825/go,Young55555/go,jmptrader/go,odeke-em/go,jdhenke/go,shines77/go,g522342435/go,kakuhiroshi/go,willjunspecial/go,jonathanmarvens/go,cookerzhu/go,xujianhai/go,sinuos/go,Badredapple/go,andrewchambers/go,arschles/golang-go,wangfakang/go-1,CAFxX/go,jacobhaven/go,AALEKH/go,jonathanmarvens/go,qskycolor/go,jasonxiong/go,dterei/go,CarterTsai/go,NunoEdgarGub1/go,skatsuta/go,cloudflare/go,yangzhongj/go,sinuos/go,ErikDubbelboer/go,qskycolor/go,myPublicGit/go,momchil-velikov/go,ErikDubbelboer/go,monetate/go,vsdutka/go,yuhengye/go,ObjectiveJoe/go,ganboing/go-esx,Badredapple/go,springning/go,albertjin/golang-go,mwhudson/go,ErikDubbelboer/go,ganboing/go-esx,samanalysis/go,roth1002/go,ichu501/go,zcwfeng/go,shines77/go,jonahglover/go,xiaobodu/go,albertjin/golang-go,theif519/go,JioCloud/go,snowsnail/go,ifagnosticism/go,uileyar/go,roth1002/go,CiscoCloud/go,xujianhai/go,donnel6809/go,cookerzhu/go,theif519/go,CAFxX/go,4ad/go,suncycheng/go,Endika/go,vsekhar/elastic-go,GeorgiCodes/go,roth1002/go,NunoEdgarGub1/go,linux-on-ibm-z/go,arschles/go-1,skotti/go,arschles/golang-go,CodyGuo/go,jonahglover/go,constantine001/go,vishsingh/go,xiaobodu/go,leeric92/go,arschles/go-1,undergrowthlinear/go,lihuanghai/go,dterei/go,Samurais/go,akutz/go,kakuhiroshi/go,vanloswang/go,roth1002/go,joshsammut/go,cyberroadie/go,miolini/go,zcwfeng/go,qskycolor/go,mdp/go,alex-zhang/go,famorted/go,xiuzhifu/go,CodyGuo/go,NunoEdgarGub1/go,CiscoCloud/go,leeric92/go,honsiorovskyi/go,albertjin/golang-go,XuYunnan/go,cainiaocome/go,yangzhongj/go,famorted/go,momchil-velikov/go,monetate/go,derekmarcotte/go,Cofyc/go,malvira/go,GeorgiCodes/go,nawawi/go,malvira/go,xujianhai/go,danielsoro/go,jdeng/go,uileyar/go,constantine001/go,skatsuta/go,dafyddcrosby/go,danycoro/go,JioCloud/go,zcwfeng/go,arschles/go-1,jameskumar/go,Cofyc/go,jefby/go,yuhengye/go,famorted/go,Endika/go,kevinc0825/go,Stan-Lin-/go,josharian/go,XuYunnan/go,ifagnosticism/go,sndnvaps/go,parkdy/go,jameskumar/go,uileyar/go,cloudflare/go,dterei/go,undergrowthlinear/go,undergrowthlinear/go,odeke-em/go,uileyar/go,vishsingh/go,yangzhongj/go,leeric92/go,kakuhiroshi/go,g522342435/go,dafyddcrosby/go,chinanjjohn2012/go,jmptrader/go,leeric92/go,beealone/go,kakuhiroshi/go,uileyar/go,beealone/go,jonasi/go,ichu501/go,NichoZhang/go,parkdy/go,arschles/golang-go,cainiaocome/go,rentongzhang/go,lihuanghai/go,rentongzhang/go,andrewchambers/go,greyhwndz/go,constantine001/go,honsiorovskyi/go,arschles/go-1,kim-racktop/go,samanalysis/go,Cofyc/go,parkdy/go,AALEKH/go,alex-zhang/go