Start Relay Resolver Docs with basic examples

[youngkidwarrior]

Created these based off the part of resolvers I have used. I tried to take a stab at graphql fragment arguments, but I have never had to use those so not sure if correct

I just used the UserGreeting example the relay docs used. We might want a more "rescripty" example that shows off how well resolvers work with Variants and switch statement

TODO:

• [ ] Check graphql argument code and make sure it is correct
• [ ] Write docs passing runtime arguments

[zth]

I haven't tried passing JS arguments to resolvers in RescriptRelay yet myself. I would assume we need some deeper integration for that to work.

[youngkidwarrior]

Okay, I'll take that part out for now

[zth]

Superseded by recent doc updates. Thanks for the effort anyway!