Update Modern-Mutations.md (#3071)
Update Modern-Mutations.md (#3071)

Summary:
This change is related to PR https://github.com/facebook/relay/pull/2937
Pull Request resolved: https://github.com/facebook/relay/pull/3071

Reviewed By: alunyov

Differential Revision: D22181382

Pulled By: kassens

fbshipit-source-id: 49c009feee6185ea4f85ca15fcbf90d212120688

josephsavona/relay,xuorig/relay,kassens/relay,xuorig/relay,josephsavona/relay,yungsters/relay,yungsters/relay,wincent/relay,voideanvalue/relay,wincent/relay,wincent/relay,wincent/relay,facebook/relay,wincent/relay,voideanvalue/relay,xuorig/relay,facebook/relay,facebook/relay,voideanvalue/relay,atxwebs/relay,josephsavona/relay,atxwebs/relay,kassens/relay,facebook/relay,voideanvalue/relay,kassens/relay,yungsters/relay,xuorig/relay,wincent/relay,xuorig/relay,xuorig/relay,kassens/relay,facebook/relay,kassens/relay,voideanvalue/relay,atxwebs/relay,facebook/relay,voideanvalue/relay,atxwebs/relay,kassens/relay