Updated docs theme

[cvanelteren]

For V2 I think it is apt to give the docs pages an overhaul. Currently the docs are functional but look dated and typical to a lot of sphinx docs. This PR modernizes the feel of the docs, while keeping the charm of the original.

Core should be:

• Functionality: the website should serve as a API reference and tutorial page, providing clear overview of the links so that the user gets where he wants to go without unncessary clutter
• Style: the style should be modern but not too flasy with toggles to hide and focus on the content
• Performant: loads should not take excessively long.

Was first thinking on moving it to Astro but that is too much work.

Partially addresses #582