* Rewrite "adding React to existing app"
Fixes#988
* Some copy
* typo
* Update babel instructions
* Update umd link
* Add prod minification section
* Show "button" example in several targets
* wip
* More
* More
* tweak
* yas
* Multi root tip
* moaar
* alot
* Tweak links
* Explain better
* better lead
* tweaks
* tweaks
* wording
* More reassuring tone
* Grammar
* wording
* feedback from readers
* Use id, not class
* More nits
* Re-add a useful section
logo-large was a custom version of the logo made just for the banner background. It was also scaled up manually rather than taking advantage of svg's inherit scaling. This change reduces its size, makes it just a plain white version of the react logo, and moves most of the custom stuff into css. It also moves it from the static folder, over to the icons folder where it can be imported as a url.
Now examples are trasnformed to GraphQL during build and assembled by the index template. This makes them easier to edit and tie in with their associated markdown description.
I discovered this inconsistency that caused the parentheses to appear/disappear when you toggle the "JSX" button. It also seems like we don't use parentheses for arrow functions with one argument, so this PR makes this behavior consistent.