Document the other crates in the codebase in the contrib guide.
Document the other crates in the codebase in the contrib guide.

rust-lang/cargo,rust-lang/cargo,nipunn1313/cargo,eminence/cargo,rust-lang/cargo,rustyhorde/cargo,rust-lang/cargo,rustyhorde/cargo,rustyhorde/cargo,eminence/cargo,nipunn1313/cargo,rustyhorde/cargo,eminence/cargo,nipunn1313/cargo,eminence/cargo,nipunn1313/cargo