[DOC] Wishlist for the Documentation

[smehringer]

Description

This issue can track nice-to-have but not-important features.

• [ ] Link labels to new documentation
• [ ] Check if we can mark a group \noapi and propagate this to all entities within the group
• [ ] Check if we can put "deprecated" in the class tree ("Class" -> "Class deprecated", etc.)
• [ ] About should come first in the list? Reorder thingies
• [ ] https://github.com/seqan/product_backlog/issues/406