Add docs about language plugin that emits uncommented Flow types (#2700)
Add docs about language plugin that emits uncommented Flow types (#2700)

Summary:
Some editors/IDEs do not understand Flow properly unless it's in plain source. This PR adds information about a community maintained language plugin for the compiler that emits the Flow types as plain source instead of inside comments.
Pull Request resolved: https://github.com/facebook/relay/pull/2700

Differential Revision: D15296532

Pulled By: jstejada

fbshipit-source-id: 4f306c2305418eb9ddceb60db3cca25aa8779b24

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