Docs facelift

[vytas7]

Look into an alternative docs theme as the current one (Alabaster) is not too appealing and still exhibits various glitches despite extensive tweaking.
Maybe @pradyunsg's furo could work well for us?

[CaselIT]

Furo seems to be extremely popular, with many projects adopting it.

Another similar one seems to be the pydata one https://pydata-sphinx-theme.readthedocs.io/en/stable/index.html, but I'm not sure how popular it is outside of the pydata circle (polars uses it and as far as I know it's not in the pydata org)

[vytas7]

A couple of years ago I chose book theme for our internal dev portal at work, it's really nice too. But I think Furo has some relation to it, because they feel similar.

Edit: Furo seems independent, probably just convergent evolution. But book theme does originate from pydata you mentioned.