raft: more doc updates.
raft: more doc updates.

Including parallelism of persist and send, cancellation of
ConfChanges, and the risks of two-node clusters.

nieanan/etcd,hpcloud/etcd,xebitstudios/etcd,qiaochao911/etcd,xueshanf/etcd,insionng/etcd,jchauncey/etcd,yifan-gu/etcd,sofuture/etcd,ajityagaty/etcd,ylong/etcd,kingland/etcd,jmptrader/etcd,yyljlyy/etcd,cockroachdb/etcd,gae123/etcd,luxas/etcd,armstrongli/etcd,xiang90/etcd,YuleiXiao/etcd,ajityagaty/etcd,barakmich/etcd,plasticbox/etcd,yichengq/etcd,jravetch/etcd,hzy001/etcd,barakmich/etcd,spacejam/etcd,mischief/etcd,Timer/etcd,HideoYamauchi/etcd,oscarrr110/etcd,achanda/etcd,ajityagaty/etcd,csuideal/etcd,nekto0n/etcd,vimalk78/etcd,beni55/etcd,delkyd/etcd,dannysauer/etcd,chenbaihu/etcd,youxidev/etcd,zaphod-concur/etcd,handsomesun/etcd,iamqizhao/etcd,junxu/etcd,pengzj/etcd,cognusion/etcd,ecnahc515/etcd,whuwxl/etcd,offscale/etcd,steveeJ/etcd,mqliang/etcd,TheHippo/etcd,mischief/etcd,svdata/etcd,ravigadde/etcd,Eagle-X/etcd,tguangch/etcd,jonboulle/etcd,heyitsanthony/etcd,mitake/etcd,snailwalker/etcd,mitake/etcd,sebrandon1/etcd,improbable-io/etcd,Winslett/etcd,cockroachdb/etcd,rchicoli/etcd,achanda/etcd,es-chow/etcd,njucslqq/etcd,imzhulei/etcd,plasticbox/etcd,mike-lerch/etcd,gityf/etcd,princeqjzh/etcd,betawaffle/etcd,StorReduce/etcd,wfxiang08/etcd,coreos/etcd,handsomesun/etcd,xychu/etcd,gtank/etcd,qqsun8819/etcd,luxas/etcd,combk8s/etcd,chipironcin/etcd,delkyd/etcd,gosharplite/etcd,visheshnp/etcd,arthurcolle/etcd,dnaeon/etcd,bdarnell/etcd,lumjjb/etcd,mkumatag/etcd,jlamillan/etcd,hpcloud/etcd,gyuho/etcd,improbable-io/etcd,wantonsolutions/dinv-etcd,shafreeck/etcd,msanterre/etcd,jchauncey/etcd,HideoYamauchi/etcd,ktateish/etcd,glensc/etcd,purpleidea/etcd,mkumatag/etcd,etcd-io/etcd,nkhare/etcd,hongbinz/etcd,mickep76/etcd,xychu/etcd,insionng/etcd,wowsoso/etcd,zaphod-concur/etcd,sebrandon1/etcd,gosharplite/etcd,joshix/etcd,insequent/etcd,princeqjzh/etcd,devfreesg/etcd,swingbach/etcd,bspline/etcd,whuwxl/etcd,Eagle-X/etcd,sinsharat/etcd,armstrongli/etcd,tangkun75/etcd,hongbinz/etcd,onlyjob/etcd,msanterre/etcd,cchamplin/etcd,rnaveiras/etcd,xebitstudios/etcd,freeloop1114/etcd,fgbreel/etcd,combk8s/etcd,glensc/etcd,a-robinson/etcd,njucslqq/etcd,svdata/etcd,Yhgenomics/etcd,freeloop1114/etcd,li-ang/etcd,chipironcin/etcd,polvi/etcd,QuantiumTechnology/etcd,QuantiumTechnology/etcd,linuxcer/etcd,tamird/etcd,sinsharat/etcd,pengzj/etcd,qiaochao911/etcd,sebschrader/etcd,oscarrr110/etcd,buaazp/etcd,vimalk78/etcd,openedbox/etcd,westhood/etcd,cchamplin/etcd,sofuture/etcd,linuxcer/etcd,coreos/etcd,dnaeon/etcd,junxu/etcd,mwitkow-io/etcd,dannysauer/etcd,fasaxc/etcd,Yhgenomics/etcd,siddontang/etcd,es-chow/etcd,lzbgt/etcd,rnaveiras/etcd,yichengq/etcd,arthurcolle/etcd,jonboulle/etcd,bakins/etcd,CrazyJvm/etcd,shafreeck/etcd,lorneli/etcd,hongchaodeng/etcd,pauldallen/etcd,spacejam/etcd,imzhulei/etcd,xdlinear/etcd,shakefu/etcd,nieanan/etcd,westhood/etcd,bspline/etcd,crandles/etcd,sayden/etcd,dalanlan/etcd,yifan-gu/etcd,njharman/etcd,raoofm/etcd,offscale/etcd,olark/etcd,asim/etcd,mwitkow/etcd,hroyrh/etcd,snailwalker/etcd,jeremyeder/etcd,ktateish/etcd,lorneli/etcd,fgbreel/etcd,giantswarm/etcd,yudai/etcd,pauldallen/etcd,steveeJ/etcd,asim/etcd,SivagnanamCiena/etcd,SivagnanamCiena/etcd,hzy001/etcd,xueshanf/etcd,njharman/etcd,shawnps/etcd,heyitsanthony/etcd,jmptrader/etcd,li-ang/etcd,Timer/etcd,xiang90/etcd,etcd-io/etcd,ravigadde/etcd,jeremyeder/etcd,CrazyJvm/etcd,hongchaodeng/etcd,gae123/etcd,mwitkow-io/etcd,yudai/etcd,axingblog/etcd,nekto0n/etcd,iamqizhao/etcd,gyuho/etcd,kingland/etcd,onlyjob/etcd,nkhare/etcd,bdarnell/etcd,elimisteve/etcd,jefby/etcd,buaazp/etcd,devfreesg/etcd,gouyang/etcd,mike-lerch/etcd,mkumatag/etcd,endocode/etcd,lumjjb/etcd,tguangch/etcd,tempbottle/etcd,YuleiXiao/etcd,OyTao/etcd_learning,siddontang/etcd,raoofm/etcd,rchicoli/etcd,a-robinson/etcd,jefby/etcd,jravetch/etcd,betawaffle/etcd,fasaxc/etcd,tangkun75/etcd,wantonsolutions/dinv-etcd,cognusion/etcd,wowsoso/etcd,TheHippo/etcd,purpleidea/etcd,bluebreezecf/etcd,mwitkow/etcd,sayden/etcd,mqliang/etcd,bluebreezecf/etcd,joshix/etcd,etcd-io/etcd,axingblog/etcd,wantonsolutions/dinv-etcd,endocode/etcd,csuideal/etcd,tamird/etcd,yyljlyy/etcd,openedbox/etcd,swingbach/etcd,Winslett/etcd,tempbottle/etcd,crandles/etcd,elimisteve/etcd,glevand/coreos--etcd,hroyrh/etcd,honeyqa/etcd,shakefu/etcd,beni55/etcd,ylong/etcd,fanminshi/etcd,jlamillan/etcd,akauppi/etcd,dalanlan/etcd,fasaxc/etcd,StorReduce/etcd,chenbaihu/etcd,insequent/etcd,qqsun8819/etcd,kkaneda/etcd,lzbgt/etcd,mickep76/etcd,olark/etcd,bakins/etcd,rnaveiras/etcd,giantswarm/etcd,mqliang/etcd,visheshnp/etcd,OyTao/etcd_learning,shawnps/etcd,sebschrader/etcd,kkaneda/etcd,wfxiang08/etcd,polvi/etcd,youxidev/etcd,fanminshi/etcd,glycerine/etcd,akauppi/etcd,glevand/coreos--etcd,xdlinear/etcd,glycerine/etcd,gouyang/etcd,honeyqa/etcd,ecnahc515/etcd,gtank/etcd,gityf/etcd