Explanation

Explanation, or discussions, clarify and illuminate a particular topic. They broaden the documentation’s coverage of a topic.

They are understanding-oriented.

Explanations can equally well be described as discussions; they are discursive in nature. They are a chance for the documentation to relax and step back from the software, taking a wider view, illuminating it from a higher level or even from different perspectives. You might imagine a discussion document being read at leisure, rather than over the code.