Provide non-changing link for lecture notes uploads [low-prio]

[Splines]

A user requested the following feature:

Many lecturers don't provide the lecture notes in their entirety at the beginning of a semester. In this case, students would benefit from non-changing URLs to the lecture notes stored in MaMpf, even when the notes are updated. This would allow them to bookmark the link such that access to the notes is quicker than having to go through the menus in MaMpf.