Fix typo in Relay Store docs
Fix typo in Relay Store docs

Summary:
s/inserEdgeAfter/insertEdgeAfter
Closes https://github.com/facebook/relay/pull/2270

Differential Revision: D6682800

Pulled By: kassens

fbshipit-source-id: 2ebd08b96c8267da959c32ec38eab006ba21afa6

atxwebs/relay,xuorig/relay,wincent/relay,josephsavona/relay,voideanvalue/relay,freiksenet/relay,facebook/relay,yungsters/relay,facebook/relay,kassens/relay,josephsavona/relay,xuorig/relay,facebook/relay,cpojer/relay,dbslone/relay,zpao/relay,voideanvalue/relay,iamchenxin/relay,freiksenet/relay,facebook/relay,cpojer/relay,wincent/relay,josephsavona/relay,voideanvalue/relay,freiksenet/relay,xuorig/relay,atxwebs/relay,voideanvalue/relay,wincent/relay,atxwebs/relay,dbslone/relay,facebook/relay,kassens/relay,kassens/relay,zpao/relay,atxwebs/relay,yungsters/relay,voideanvalue/relay,voideanvalue/relay,xuorig/relay,zpao/relay,iamchenxin/relay,wincent/relay,yungsters/relay,facebook/relay,cpojer/relay,kassens/relay,iamchenxin/relay,iamchenxin/relay,xuorig/relay,kassens/relay,wincent/relay,kassens/relay,cpojer/relay,wincent/relay,xuorig/relay