More musical examples, more examples

[Bubobubobubobubo]

It's hard to document something that is still under heavy dev. However, musical examples are super useful to teach people how to work with the software:

• [x] Examples section with didactic pieces: sampling, MIDI, organisation, trivia, etc...
• [x] Teaching the user how to move in the interface to compose complex musical pieces
• [x] More examples for each section (accordion?) showing different use cases.

[Bubobubobubobubo]

This initial documentation work is now over but documentation quality should definitely be improved. I've noticed in particular, while working on another issue:

• that some sections are unfinished (hello patterns). This probably has something to do with the fact that the implementation of a proper pattern system hasn't been done yet outside of Ziffers.
• that the musical quality of most examples is really poor. It's probably a good idea to take an afternoon to improve on this quite dramatically because the most important sections are really depressing to listen to at the moment.
• that some sections say a lot about the unfinished state of some features. There are a lot of inconsitencies on the MIDI page and this has to do with the fact that MIDI has never been used in a live context since Topos was created. An update is required, and this should go with another PR to improve MIDI support!