Clarify plug pipeline docs in `Phoenix.Controller`
Clarify plug pipeline docs in `Phoenix.Controller`

The phrasing made it sound like a controller is a
form of router.
ugisozols/phoenix,thegrubbsian/phoenix,KazuCocoa/phoenix,rodrigues/phoenix,keathley/phoenix,kholbekj/phoenix,doron2402/phoenix,scrogson/phoenix,iguberman/phoenix,wsmoak/phoenix,seejee/phoenix,rafbgarcia/phoenix,mschae/phoenix,Smulligan85/phoenix,phoenixframework/phoenix,jwarwick/phoenix,rodrigues/phoenix,bdtomlin/phoenix,sadiqmmm/phoenix,tony612/phoenix,SmartCasual/phoenix,bsmr-erlang/phoenix,michalmuskala/phoenix,michalmuskala/phoenix,FND/phoenix,Fluxuous/phoenix,0x00evil/phoenix,kevinold/phoenix,wicliff/phoenix,justnoxx/phoenix,Dahoon/phoenix,mvidaurre/phoenix,greyhwndz/phoenix,lono-devices/phoenix,evax/phoenix,eksperimental/phoenix,yonglehou/phoenix,iStefo/phoenix,xtity/simple_phoenix,mschae/phoenix,Gazler/phoenix,stevedomin/phoenix,sdnorm/phoenix,jeffweiss/phoenix,seejee/phoenix,switchflip/phoenix,phoenixframework/phoenix,y-yagi/phoenix,cas27/phoenix,Smulligan85/phoenix,lono-devices/phoenix,ericmj/phoenix,esbullington/phoenix-1,linearregression/phoenix,mitchellhenke/phoenix,optikfluffel/phoenix,gjaldon/phoenix,Joe-noh/phoenix,jwarwick/phoenix,optikfluffel/phoenix,omotenko/phoenix_auth,andrewvy/phoenix,hotvulcan/phoenix,korobkov/phoenix,optikfluffel/phoenix,henrik/phoenix,dmarkow/phoenix,vic/phoenix,stefania11/phoenix,trarbr/phoenix,robhurring/phoenix,Kosmas/phoenix,phoenixframework/phoenix,lancehalvorsen/phoenix,bsodmike/phoenix,keathley/phoenix,vic/phoenix,DavidAlphaFox/phoenix,brucify/phoenix,daytonn/phoenix,korobkov/phoenix,yoavlt/phoenix,nshafer/phoenix,jasond-s/phoenix,robomc/phoenix,GabrielNicolasAvellaneda/phoenix,mobileoverlord/phoenix,jxs/phoenix,ybur-yug/phoenix,elliotcm/phoenix,Joe-noh/phoenix,JHKennedy4/phoenix,foxnewsnetwork/phoenix,CultivateHQ/phoenix,0x00evil/phoenix,Kosmas/phoenix,stevedomin/phoenix,manukall/phoenix,javimolla/phoenix,andrewvy/phoenix,nshafer/phoenix,bsmr-erlang/phoenix,StevenNunez/phoenix,rafbgarcia/phoenix,trarbr/phoenix,VictorZeng/phoenix,gjaldon/phoenix,romul/phoenix,Eventacular/phoenix,jamilabreu/phoenix,omotenko/phoenix_auth,ahmetabdi/phoenix,Rumel/phoenix,nshafer/phoenix,DavidAlphaFox/phoenix,CD1212/phoenix,beni55/phoenix,iStefo/phoenix,arthurcolle/phoenix,pap/phoenix,mobileoverlord/phoenix,ephe-meral/phoenix,doomspork/phoenix,wsmoak/phoenix,Gazler/phoenix,eksperimental/phoenix,maxnordlund/phoenix,marcioj/phoenix,begleynk/phoenix,ericmj/phoenix,mvidaurre/phoenix,evax/phoenix,jamilabreu/phoenix,CultivateHQ/phoenix,ephe-meral/phoenix,manukall/phoenix,Rumel/phoenix,fbjork/phoenix,0x00evil/phoenix,dmarkow/phoenix,paulcsmith/phoenix,Ben-Evolently/phoenix,cas27/phoenix,milafrerichs/phoenix,kyledecot/phoenix,jeffkreeftmeijer/phoenix,nickgartmann/phoenix,nicrioux/phoenix,ybur-yug/phoenix,rafbgarcia/phoenix,kidaa/phoenix,mitchellhenke/phoenix,safi/phoenix,hsavit1/phoenix,pap/phoenix,lancehalvorsen/phoenix