Documentation

[pckroon]

This is my start for updating the documentation. I still want to have a go at the tutorials folder, which is currently pretty much empty. I think I'll add one on how to add a residue

The built docs for this PR can be found here: https://vermouth-martinize.readthedocs.io/en/documentation/

[fgrunewald]

@pckroon just FYI for more simulation heavy tutorial files we also have the martinze2 example repro

[pckroon]

Oh excellent! I'll refer to that

[pckroon]

The built docs for this PR can be found here: https://vermouth-martinize.readthedocs.io/en/documentation/