Unfortunately, the raspiBackup documentation on this website had become increasingly disorganized over time. Fortunately, someone noticed this and offered to create a raspiBackup documentation page on GitHub using mdbook. He uploaded all existing raspiBackup pages from this website to GitHub, built a framework so the pages could be organized and easily edited—which was urgently needed—and finally ensured that any changes to the documentation are automatically republished.
I don’t have the technical know-how to do this myself, and I’m extremely grateful to rpi-simonz for setting everything up for me, making the raspiBackup documentation clearer and much easier to maintain and edit.
In short: The complete raspiBackup documentation can now be found here. Questions about raspiBackup can be asked here, and please report any issues here on GitHub (GitHub registration is free ;-) ) There’s also a raspiBackup thread on the English RaspberryPi Forum where you can ask questions about raspiBackup.