Add some documentation for optimisticResponse
Add some documentation for optimisticResponse

Reviewed By: leebyron

Differential Revision: D4904541

fbshipit-source-id: 32031e99c3a26184ae085a543f0fb83f85ff9ac6

josephsavona/relay,xuorig/relay,voideanvalue/relay,voideanvalue/relay,freiksenet/relay,yungsters/relay,iamchenxin/relay,voideanvalue/relay,cpojer/relay,yungsters/relay,atxwebs/relay,kassens/relay,apalm/relay,josephsavona/relay,facebook/relay,atxwebs/relay,facebook/relay,apalm/relay,benjaminogles/relay,yungsters/relay,wincent/relay,kassens/relay,kassens/relay,zpao/relay,rosskevin/relay,kassens/relay,dbslone/relay,benjaminogles/relay,iamchenxin/relay,voideanvalue/relay,dbslone/relay,apalm/relay,cpojer/relay,iamchenxin/relay,chirag04/relay,facebook/relay,freiksenet/relay,josephsavona/relay,chentsulin/relay,zpao/relay,xuorig/relay,chirag04/relay,atxwebs/relay,atxwebs/relay,chentsulin/relay,voideanvalue/relay,benjaminogles/relay,chirag04/relay,wincent/relay,wincent/relay,kassens/relay,facebook/relay,iamchenxin/relay,rosskevin/relay,facebook/relay,xuorig/relay,facebook/relay,voideanvalue/relay,zpao/relay,kassens/relay,chentsulin/relay,xuorig/relay,wincent/relay,wincent/relay,xuorig/relay,cpojer/relay,xuorig/relay,wincent/relay,freiksenet/relay,cpojer/relay