Documentation cleanup: fix typos, grammar, and naming consistency

[DimitriPapadopoulos]

TODO:

• Unit tests and/or doctests in docstrings
• Tests pass locally
• Docstrings and API docs for any new/modified user-facing classes and functions
• Changes documented in docs/release.rst
• Docs build locally
• GitHub Actions CI passes
• Test coverage to 100% (Codecov passes)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 2.14%. Comparing base (e0ddee6) to head (88b71e0).

❗ There is a different number of reports uploaded between BASE (e0ddee6) and HEAD (88b71e0). Click for more details.

HEAD has 20 uploads less than BASE

Flag	BASE (e0ddee6)	HEAD (88b71e0)
	23	3

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #814       +/-   ##
==========================================
- Coverage   99.33%   2.14%   -97.19%     
==========================================
  Files          26      26               
  Lines         898     884       -14     
==========================================
- Hits          892      19      -873     
- Misses          6     865      +859     

see 25 files with indirect coverage changes

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[DimitriPapadopoulos]

@d-v-b I had to move this from docs/compression/zstd.rst. Not sure if it works with automethod, but at least it should fix the missing decode documentation.