Update to new GraphQL ppx

[huy-nguyen]

The ppx mentioned in the README is not maintained anymore (announcement). It also may not support BuckleScript 6 (source). Please consider using this one instead.

[gugahoa]

I think it's worth mentioning both, and let users choose

[huy-nguyen]

I see that the old ppx is specified explicitly in bsconfig.json:

https://github.com/FormidableLabs/reason-urql/blob/d6a2dbf6de3794cc218ba08828f068cf4445f2f4/bsconfig.json#L32

Does that require people to install the old one if they just want to use the new one?

[Schmavery]

I don't think the ppx is used anywhere in the library, I wouldn't be surprised if that option could be safely removed from the bsconfig.

That said, I think it makes sense to mention graphql_ppx_re in the README as a first option, maybe something like you can use [graphql_ppx_re](link) (which is based on [graphql_ppx](link)).

As things move towards bs-platform 6, it seems like it would be nice to have the support and to guide people towards the more active library.

[parkerziegler]

@Schmavery is correct, I believe that flag can be safely removed. The only reason it was included was back when I was first prototyping the examples in repo, but we are long past that point. If anyone wants to make a PR to remove it and update the docs, I'll be happy to review – otherwise I can get to it tomorrow! I do think it'd be good to direct folks towards the more actively maintained lib, so if folks are interested in contributing you could also update the in-repo examples!