feat(/* branch: string): Allow branch queries to other versions

[sudojunior]

This is something I've wanted to do for a while, only hitch being the version either has to be optional (and after all the required arguments) or an entirely new command to specifically handle versioning (which is what Eris Docs does /vdocs). It's not a bad way of handling distinct logic between latest and {branch/tag/ref}.

Some files on the docs branch refer to branches that may have been merged or outright removed, but their manifest remains - docs site has filtered this out.

• /code *
• /docs *

[sudojunior]

Added in #70