Consider splitting the documentation into several modules

Right now the qtinterfaceframework documentation consist of 3 modules:

• QtInterfaceFramework
• QtIfMedia
• QtIfVehicleFunctions

The last two are reference modules.

It should be decided whether all those modules should still live in a joint documentation, or whether it should be splitted, similar to https://doc.qt.io/qt-5/qtqml-index.html and https://doc.qt.io/qt-5/qtquick-index.html

In case of a split, the license attributions needs to be fixed accordingly.