Fix up the flow parser npm README
Fix up the flow parser npm README

Summary:
Noticed the readme was out of date. Technically calling `flow.parse("1+1")` doesn't work without the options.

Looks like this: https://gist.github.com/gabelevi/6b351dbe28d2ecaaa285c87ab8c61e1f
Closes https://github.com/facebook/flow/pull/1859

Reviewed By: mroch

Differential Revision: D3359931

Pulled By: gabelevi

fbshipit-source-id: 12ee917c798d37fe7d70554bf33c4b7c76517387

ForbesLindesay/flow,gabelevi/flow,jgrund/flow,cesarandreu/flow,claudiopro/flow,gabelevi/flow,gabelevi/flow,facebook/flow,MichaelDeBoey/flow,samwgoldman/flow,chenglou/flow,JonathanUsername/flow,jgrund/flow,jdelStrother/flow,jeffmo/flow,mroch/flow,AgentME/flow,facebook/flow,AgentME/flow,TiddoLangerak/flow,gabelevi/flow,MichaelDeBoey/flow,jamesgpearce/flow,claudiopro/flow,samwgoldman/flow,gabro/flow,ForbesLindesay/flow,popham/flow,ylu1317/flow,cesarandreu/flow,cesarandreu/flow,mroch/flow,jeffmo/flow,mroch/flow,jeffmo/flow,claudiopro/flow,jdelStrother/flow,samwgoldman/flow,popham/flow,nmote/flow,mroch/flow,nmote/flow,gabelevi/flow,fletcherw/flow,mroch/flow,MichaelDeBoey/flow,jamesgpearce/flow,facebook/flow,gabelevi/flow,ForbesLindesay/flow,AprilArcus/flow,AprilArcus/flow,ForbesLindesay/flow,fletcherw/flow,gabro/flow,chenglou/flow,jeffmo/flow,JonathanUsername/flow,AgentME/flow,facebook/flow,gabro/flow,AgentME/flow,AprilArcus/flow,popham/flow,jgrund/flow,JonathanUsername/flow,cesarandreu/flow,mroch/flow,facebook/flow,fletcherw/flow,nmote/flow,AgentME/flow,jamesgpearce/flow,MichaelDeBoey/flow,ylu1317/flow,nmote/flow,popham/flow,samwgoldman/flow,TiddoLangerak/flow,nmote/flow,fletcherw/flow,AprilArcus/flow,claudiopro/flow,JonathanUsername/flow,jgrund/flow,ylu1317/flow,samwgoldman/flow,TiddoLangerak/flow,popham/flow,jamesgpearce/flow,chenglou/flow,jamesgpearce/flow,facebook/flow,jdelStrother/flow,mroch/flow,chenglou/flow,claudiopro/flow,jdelStrother/flow,ForbesLindesay/flow,popham/flow,jeffmo/flow,jdelStrother/flow,ylu1317/flow,nmote/flow,gabelevi/flow,ForbesLindesay/flow,ylu1317/flow,gabro/flow,JonathanUsername/flow,facebook/flow,nmote/flow,chenglou/flow,jamesgpearce/flow,fletcherw/flow,jdelStrother/flow,gabro/flow,JonathanUsername/flow,samwgoldman/flow,TiddoLangerak/flow,AprilArcus/flow,TiddoLangerak/flow,popham/flow,MichaelDeBoey/flow,fletcherw/flow,jamesgpearce/flow,AprilArcus/flow,chenglou/flow,jgrund/flow,gabro/flow,jgrund/flow,jeffmo/flow,samwgoldman/flow,JonathanUsername/flow