Add "Static Type Checking" section to docs

[bvaughn]

This concern was originally raised by @barbu110 via facebook/react/issues/9684

Refer to the discussion on that thread for more backstory.

The outcome of that discussion is: Create a new guide called "Static Type Checking" that shows how to use React from Flow and TypeScript and describes main API definitions.

[ishankbahl]

Hi @bvaughn , I would like to work on this one.

[bvaughn]

This issue is all yours! 😄

I've added an "in-progress" label so that others will know not to start work on the issue. If you change your mind about the issue, no worries! Just let me know so that I can remove the label and free it up for someone else to claim.

Cheers!

[ishankbahl]

@bvaughn
Just saw that entire API reference has been added to the flow website
( https://flow.org/en/docs/react/types/ ). Is this guide necessary now or not?

[bvaughn]

This issue originally covered TypeScript as well as Flow.

Looks like TypeScript also has a brief introduction to TypeScript + React on their site.

Maybe it's okay to have a minimal section for Flow and TypeScript integration and then link to the official docs pages for more details?

[ishankbahl]

@bvaughn made a PR for this two days back.

[bvaughn]

Closed by #189

Thanks Ishank!