Add sphinx-tippy

[LecrisUT]

Let's make it pretty 🙂.

There is also sphinx-hoverxref, but I forgot what the issue was with that and markdown support

[henryiii]

Getting a lot of WARNING: Could not fetch RTD data for https://docs.python.org/3/library/functions.html#object: 'content' [tippy.rtd] [tippy.rtd], is there some config missing?

[LecrisUT]

Oh, for some reason I thought python has RTD metadata similar to sphinx. Probably I mixed up those two in my head.

[LecrisUT]

Didn't realize it until I got the mail notification, but 🎉 for #1000

[henryiii]

First thing I noticed. ;)