docs: update treewide documentation

[Nytelife26]

Relevant issues

Some content introduced here has been borrowed from and will be superseded by #1437. Includes a draft of #1408.

Brief

Update project documentation in advance of Proselint 0.15.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.12%. Comparing base (02e85a8) to head (f21d6ce).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1445   +/-   ##
=======================================
  Coverage   91.12%   91.12%           
=======================================
  Files         100      100           
  Lines        1037     1037           
=======================================
  Hits          945      945           
  Misses         92       92           

Flag	Coverage Δ
macos-latest	90.54% <ø> (ø)
py3.10	91.12% <ø> (ø)
py3.11	91.12% <ø> (ø)
py3.12	91.12% <ø> (ø)
py3.13	90.54% <ø> (ø)
py3.14	90.54% <ø> (ø)
ubuntu-latest	90.54% <ø> (ø)
windows-latest	91.12% <ø> (ø)

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