Guidelines and HOWTOs/Change the default wallpaper

1. Get VDG agreement on the wallpaper.
2. Have git checkouts of the breeze, plasma-workspace, plasma-desktop, and plasma-workspace-wallpapers git repos.
3. git clone https://invent.kde.org/niccolove/kde-wallpaper-updater and enter the kde-wallpaper-updater folder.
4. Either delete the file named .magic.config, or edit it to have the correct repo paths on your system.
5. Install the gitpython python module using either your distro's package manager, or else python3 -m pip install gitpython if you prefer to install python modules in your user folder rather than systemwide.
6. Run python3 updater.py and follow the instructions.
7. In each of breeze, plasma-workspace, plasma-desktop, and plasma-workspace-wallpapers repos, push your branch to origin and open a merge request. Merge once the pipeline is green!