Enable more elaborate feedback for exercises

Oftentimes, it was mentioned that a like button is great, but it does not tell what is good about an exercise. Therefore, it was recommended to extend this feature to a more qualitative feedback form, where a user can rate different aspects of a resource. These aspects could be for example, the problem definition, difficulty, duration etc. Regarding feedback people also proposed a direct message functionality, in order to receive feedback, which might be negative in a more private way to avoid people being scared of uploading as they might be criticized. Furthermore, some also wanted a comment field for general feedback as it helps on the one hand to choose an exercise and on the other hand it is an other possibility of feedback

• Enable comments (with opt-in controlled by user?)
• Create a more elaborate feedback form (similar to Booking platforms?)
• Enable direct messages