Improve documentation navigation in documentation modules

In the current documentation state, you may not be able to intuitively find all the topics within the module. You cannot see what is described in the current module. We can improve this situation in both online and offline (displayed in Qt Creator) docs:

• For online and offline docs: provide a tree of topics for the current module within a module's index page. This may look almost like here or even better: https://doc.qt.io/qt-6/qtquickcontrols-index.html#articles-and-guides 
• For offline docs: organize topics in a nice tree visible in Qt Creator, like this or maybe better. 
  

Each module should include a better navigation.