doc-gen#172 instance lists for pi and Type

Stream: PR reviews

[Eric Wieser]

This PR won't fall on the queue since it's in a different repo, so drawing attention to it here. It adds this fairly sparse page:

https://leanprover-community.github.io/mathlib_docs_demo/foundational_types.html

[Eric Wieser]

A follow-up is at doc-gen#173, the same link as above goes to the preview

[Eric Wieser]

Could someone take a look at the above? I'd like to get it merged so that I start on my next doc-gen PR

[Eric Wieser]

Maybe @Bryan Gin-ge Chen or @Gabriel Ebner?

[Gabriel Ebner]

Could you please also make PRs / file as todo issues to doc-gen4?

[Eric Wieser]

https://github.com/leanprover/doc-gen4/issues/90

[Eric Wieser]

I'm not familiar enough with Lean4 to attempt a forward-port