Document the Hipcheck release workflow

[alilleybrinker]

Release workflow:

• Run cargo xtask changelog -b to generate a draft changelog.
• Use that to write a changelog entry for the new version.
• Commit the changelog, PR, merge it.
• Run cargo release <version_change> -p <crate_name> --certs-source native to check release
• Rerun the above command with the --execute flag to run. (Everything else is automated)
• cargo-release push of tag triggers cargo-dist CI
• cargo-dist CI builds artifacts, creates GitHub Release with contents pulled from changelog entry for the new version