gh-148529: Minor improvements of the struct module documentation (GH-148565)

* Document that 's' and 'p' accept bytes and bytearray.
* Fix some footnotes.
* Clarify that "string" is a byte string.
* Fix the module docstring.

Serhiy Storchaka committed 9h ago

3e5a3cb2bd222f97f793b01bc1c0f7bb62aefc31

Parent: 276f474

Committed by GitHub <noreply@github.com> on 4/27/2026, 6:30:48 PM