RFC: Remove #[crate_id]

I'm a little confused by your question, this section is referencing *today's* behavior, and I stated above that the hash is of the CrateId.

Down below, I stated that the hash is the contents of the metadata (crate attribute + command line flags). If you wanted to disambiguate your library oh github then you could add that to the crate attribute and it'd get hashed in.