[WIP] Revisiting structure part 1

| Q   | A
| --- | ---
| Doc fix? | yes
| New docs? | no
| Applies to | all
| Fixed tickets | partly #523

During this Community Hack Day, I'll try to work on the revisited doc structure.
i think we could stop saying this. instead of the `caution` it could be some less "negative" box saying that if you find mistakes or otherwise want to help, we would appreciate.

then again, the edit link at the top of cmf pages now works, so maybe we could drop the whole box. it should be kind of obvious to open source people that they can contribute and that we hope they do it...