Show relevant citations in documentation pages

We should make citing the relevant publications as simple as possible. A good step could be to list relevant publications on documentation pages.

**Implementation**

This could be a tagging system that assigns a topic to a page and then lists a set of publications for the tag: `cpl-schemes`, `mappings`, `IQN`.

We currently need to maintain a database of publications for the literature review page. So, this could also be a list of citations in page headers.

Start by reviewing the documentation pages and the existing literature review publication database. Compare the proposed topic-tagging approach with citations in page headers, then define which approach can list relevant publications and keep citations maintainable across pages.

Written by the indexing model from the issue text.