Contribution guide for people new to Rust

[jpike88]

I'd love to contribute (fixing a rule, proposing a new one via PR), but I know zero Rust. I do have experience in Java, C etc... however I've worked with Typescript for many years now.

I think that in order to stimulate more contribution and encourage more direct collaboration, a contribution guide (including setting up Rust) with an example walkthrough for designing a new rule is a good idea.

I imagine that contributors don't need to know anything beyond the bare minimum to submit/improve on a rule (as well as the quick fix implementation for that rule), so a walkthrough + quick Rust reference on the side just for syntax, stlib equivalent, etc would hopefully be enough for a guy like me to stop whining about what I want, and contribute directly.

Thoughts?