Following the release process for
https://github.com/tokio-rs/tracing/blob/master/CONTRIBUTING.md and
these changes are the only things left to commit before release.

I'd like to hopefully get this released today so we can start using this
crate internally.

Note: I need to get PR #703 and PR #678 merged before release.

Co-authored-by: Zeki Sherif <zekshi@amazon.com>
Co-authored-by: Eliza Weisman <eliza@buoyant.io>