docs: Make section def more useful

[salim-b]

Note that this section definition clearly overlaps with the glossary entry for "section". If we would convert the glossary terms to structured data, we could actually re-use them at various places. What do you think @jmooring? I can open a separate issue if you agree.

[jmooring]

convert the glossary terms to structured data

Let's leave it as-is and copy/paste when necessary, which isn't very often.

[salim-b]

Let's leave it as-is and copy/paste when necessary, which isn't very often.

In that case I'd suggest to remove this "definition-of-section" snippet from most places (e.g. like here) and instead link to the glossary term where applicable. It's confusing.