Add helper to generate docs from schema

[brandonchinn178]

Add a helper function that takes a Decoder and generate documentation from the schema, possibly in Markdown format.

[theophile-scrive]

Very interested in this!

[brandonchinn178]

@theophile-scrive Unsure when I'd be able to get around to this 😅 If you have any time and are interested in contributing, I'd really appreciate any help here!

[theophile-scrive]

@brandonchinn178 I'd love to think about it. If you have pointers of a proto-design I'm very interested. :)

[brandonchinn178]

Nothing much. I think there needs to be a normalization step; right now, the Decoder schema is pretty messy since it encodes each raw arrow step separately. Unfortunately, it's a bit necessary; there's no way to simplify (A *> B) <|> (C *> D) if someone does that. But I havent thought much deeper than that