Optimise navigation titles

[jmuheim]

As described in https://github.com/Access4all/adg/wiki/Hackday-%2316-(22th-of-October-2020)#how-to-proceed, we want to optimise the navigation titles so they are more explanative. We hope that more users will then be interested in them and click them.

Lea will give a proposal here (as text) which we then can implement.