Allow to include multiple folders from separate locations

Is your feature request related to a problem? Please describe.
Using the App for shared notes, as well as for private ones, there is still only one notes folder to share. Notes just get created there, independent of it's sharing status. Also when having a own folder-structure, it is not possible to use notes from separate folders.

Describe the solution you'd like
It would be cool, if one could just add arbitrary folders to be read by the app, that then appear just as the current categories. Advanced version of this feature would then be to allow admins to add such folders for all users within settings.

Describe alternatives you've considered

• Packing all data within one Notes Folder?
• Creating separate folders within the notes folder, that then can be shared?

Start by locating how the app currently selects its single notes folder, exposes categories, and handles shared versus private notes. Then trace any settings path for administrator configuration. Done would mean multiple user-selected folders can be read as categories, with the administrator-wide option explicitly scoped and existing note behavior preserved.