etcdctl: add extended as output format
etcdctl: add extended as output format

extended wasn't documented in the help as one of the output formats, fix
this!

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