Add a "Back to the lecture"-Button

When looking at a specific exam, a button "Back to the lecture" (or "All exams") would be nice. By pressing it, the user goes back to the site with all exams of the concerning lecture.

E.g. from https://exams.vis.ethz.ch/exams/ijx20ej0.pdf to https://exams.vis.ethz.ch/category/AdvancedMachineLearning .