The datetime docs are chalk full of detail.  This is a positive aspect,
and represents a huge amount of work by Tim Peters and A.M. Kuchling.
However, it also may function as an obstacle for beginner readers and
those simply seeking to answer a basic question or see a straightforward
usage example.  Rather than seeing an example-based explanation of
a common use-case, they are bombarded with technical detail and
edge cases.

I propose some restructuring of the datetime docs with the goal of
making them more reader-friendly.  The goal is not to eliminate any
of the detail, but to restructure things so as to bring the "everyday"
parts into more prominent real estate.

The changes here all make an effort to reflect what's espoused by
"Documenting Python" at https://devguide.python.org/documenting/.

I have some additional changes in mind but wanted to put this here now
to gauge receptiveness to the existing changes.