Mention new graphql ppx instead of old one

[huy-nguyen]

Mention new graphql ppx in docs and remove ppx from ppx_flags in bsconfig. Fixes #117. Pinging @parkerziegler.

[parkerziegler]

Thanks so much for this @huy-nguyen! Everything looks good on my end, just a few small suggested tweaks! I will also want to do some reading on graphql_ppx_re today before merging just to validate that the library returns the same Js.t shape from calling make (i.e. query, variables, and parse), since we rely on that heavily for proper type inference support. Appreciate you contributing ❤️

[parkerziegler]

Thanks again @huy-nguyen. The one thing that makes me a bit nervous about graphql_ppx_re are the unclear instructions about generating a graphql_schema.json, especially from a remote schema: https://github.com/baransu/graphql_ppx_re#usage One thing I really appreciate about graphql_ppx is that it's a one liner to get a schema from a remote server. I'll open an issue upstream asking for more clarification there. Thanks again for contributing!

[parkerziegler]

@all-contributors add @huy-nguyen for docs.

[allcontributors]

@parkerziegler

I've put up a pull request to add @huy-nguyen! 🎉