Remove automotive references in docs

QtIvi was tailored for the automotive industry and the documentation was referencing to the automotive context a lot.

Now with the rename of the module, also some other industries are of interest. The automotive references should be checked and it should be considered to rephrase them to make them more universal.

https://doc-snapshots.qt.io/qtivi-dev/backend-system.html is a good example where some rephrasing makes sense.