Doc fixes and notebooks

[jenshnielsen]

Add example notebooks to docs.

• Convert notebooks to rst as part of docs build and include in docs.
• For the notebooks to be cleanly imported they need exactly one 1 level header so change them all to have that.
• Mock the Zi so it's driver docs can be build.
• Few other small docs fixes

In general many of these notebooks needs some work. Either deleted, expanded or just checked for errors.

@QCoDeS/core

[giulioungaretti]

@jenshnielsen looking good! Let's merge now so at least they are visible, then we can fix the notebooks one at time!

[jenshnielsen]

I agree having a big pr with lots of notebook edits is just asking for merge conflict hell

[giulioungaretti]

@jenshnielsen great! Merge whenever you deem appropriate !