Provide protocol documentation

[blackwolf12333]

I couldn't immediately find documentation about the actual protocol, it would be really nice to have so others can start working on implementations for other languages (I'd be interested in building one for PHP).

[Liam-DeVoe]

Yes! This is on or shortlist. I have a draft of this and had to cut it for the release. We also plan to write a "how to write your own Hegel library" article; see #3 for that.

I'll forewarn that the protocol is still one area where we're likely to make medium breaking changes (as opposed to only expecting ~lightish breaking changes for hegel-rust and so on), but if knowing that you'd still like to write a library for it, we'd be excited to support you and fix any issues you run into. Providing resourcing for people writing and maintaining libraries using the Hegel protocol is a definite goal of ours and I'm excited to hear you're interested!