Convert the Celo protocol docs over to docusaurus.

[dckesler]

No description provided.

[dckesler]

• The documentation is inside of docs/celo-codebase/protocol/
• We should match the urls starting at https://docs.celo.org/celo-codebase/protocol
• We'll need a place in the sidebar that matches the category document at https://docs.celo.org/celo-codebase/protocol
• We may need to decide how we want our internal page reference to look. Currently https://docs.celo.org/celo-codebase/protocol has a bunch of these and they're more than just links and I'm not sure if docusaurus has a matching pre-made component for these.
• This one is a lot of small pages but they don't seem to difficult.