refactor documentation

[12rambau]

as suggested by @mariobuikhuizen, I should make small PR which make it easier to review. I open this issue to follow-up on the documentation update. I'll break it down into multiple PR.

I would like to work on the documentation and update the template that is used. my objective are the following :

• use the pydata-sphinx-theme (because thats my favorite for sphinx)
• refactor the structure of the documentation to expose the API
• try to pull information from the vuetify API
• use vuetify look & feel
• support dark theme (widget should change color when we shut down the light)