I meant to share this at the beginning of Google Season of Docs but I
couldn't find it until now. This is a talk that was shared by the GSoD
admins at some point.
https://www.youtube.com/watch?v=t4vKPhjcMZg
There's also a blog post version of the talk if you don't have time to
watch it.
https://www.divio.com/blog/documentation/
The talk does a good job of clarifying the different kinds of
documentation how they should be separated. We do a decent but not
perfect job of having this separation in our SymPy docs, and it might
help to make the separation clearer, as suggested at the end of the
talk.
Aaron Meurer