[docs] Add a reference to create-react-app-with-flow

[oliviertassinari]

Remove some unneeded dependencies raised by @cherniavskii in #9732.

[cherniavskii]

@oliviertassinari

Looks like other examples should be updated too:

1. It's better to use jssPreset, exposed in [core] Update jss plugins dependencies #9732 instead of jss-preset-default in create-react-app-with-jss:
   https://github.com/mui-org/material-ui/blob/v1-beta/examples/create-react-app-with-jss/src/withRoot.js

2. We can remove jss-preset-default, jss and react-jss from create-react-app-with-flow example, since those dependencies aren't used.

3. We can remove jss and react-jss from nextjs example, since those dependencies aren't used.

I can submit a PR

[oliviertassinari]

@cherniavskii Yes, I agree. I was sold on the idea that people don't have to add an external dependency like jss-preset-default as they can get away quickly with our preset. For instance, on my project it take 5 minutes to run yarn. (running in a Docker and compiling C dependencies every time).

[oliviertassinari]

Can you submit a new pull request? :)

[cherniavskii]

@oliviertassinari sure, I'll submit it today ;)