Produce documentation for all packages in a workspace

[Levi-Lesches]

One major disadvantage when moving from N multiple smaller repos to one mono-repo is losing the ability to host N-1 GitHub Pages websites.

It would be nice if an option like --workspace produced a docs page with documentation for all packages. The landing page would be similar to the current page, except you'd choose packages instead of libraries. Then everything else would remain the same (except the URL, probably).

[simolus3]

I'd love to have this as well. Flutter's API documentation also spans multiple packages, having something similar for package authors would be really nice: https://api.flutter.dev/