Diátaxis: Where are we?

There seems to be general consensus that diátaxis is a great theoretical model for structuring documentation.
However, using it – restructuring Python's docs – is a monumental task that needs some planning upfront.
@AA-Turner mentioned on the recent meeting that it would be good to start by charting the starting point: where on the Diátaxis chart do individual sections of the docs fall?
With that info we should be able to start planning where they should fall, and restructure/rewrite accordingly.

Start by reviewing the Diátaxis model linked in the issue and the current structure of Python’s documentation. Inventory the individual documentation sections and record where each falls on the Diátaxis chart; the work is done when that starting-point map is available for planning restructuring and rewriting.