Add to awesome-sphinxdoc

[johnpmcconnell]

https://github.com/yoloseem/awesome-sphinxdoc maintains a list of useful Sphinx extensions, and this project will be immensely useful for people like me who find themselves implementing protocols relatively often.

I thought about just submitting a pull request to that project myself, but I wasn't sure that the maintainers here would feel the project is complete/polished enough to be there yet. So I thought I should file an issue here to ensure it's on the radar.

[eric-wieser]

Feel free to do so.