Add link to more optimistic examples in Todo app
Add link to more optimistic examples in Todo app

Summary:
Add/remove/update within a list are essential operations for a wide variety of apps, and it's not yet obvious where to find those examples.

Adding a link to the Relay Modern Todo app which has several great examples.
Closes https://github.com/facebook/relay/pull/1802

Reviewed By: kassens

Differential Revision: D5154929

Pulled By: yuzhi

fbshipit-source-id: 17cf54090f18ac4717301ab73a1aea0cec3afabe

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