code-generated reference docs

> As a followup on our previous discussion (https://github.com/canonical/chisel/pull/186#discussion_r1905530295), I see your point in the code being auto-generated, but it will probably not use the Golang code as a source of truth anyway. It will either have an intermediate format like the json schema or will be manually generated. Anyway, this will not be easily encoded in any of the representations unless we do it manually.

_Originally posted by @letFunny in https://github.com/canonical/chisel-docs/pull/4#discussion_r1912927017_