[docs]: React Integration

[bennypowers]

The React integration docs should be updated to cover:

• why does react need special treatment?
• useRef for events and props
• updating ce state via ref
• lit-labs/react to make wrappers
• using slots instead of renderProps
• automatically-generated wrappers

[bennypowers]

cc @anujsi @heyMP

[bennypowers]

Anuj are you available to draft a PR for these docs?

cc @eyevana @kylebuch8

[anujsingla]

@bennypowers Yes I can do it.