Support linking to types rather than embedding for autodoc generation

[mattrunyon]

Some types (like Color) are quite long union types. I can't preview the file as it would render on salmon currently, but based on the generated markdown, the entire type is embedded into the param table. For long types, this could be quite annoying to look at if the type makes a row in the API table take up a ton of extra space.

I think we should have a list of types that are always linked to instead of embedded. And possibly a way to configure the autodoc command to embed types on a case-by-case basis.