docs: fix plural names in docs

[tlambert03]

fixes #255

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.67%. Comparing base (59a37da) to head (91cf211).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #256      +/-   ##
==========================================
- Coverage   86.69%   86.67%   -0.03%     
==========================================
  Files          25       25              
  Lines        1255     1253       -2     
==========================================
- Hits         1088     1086       -2     
  Misses        167      167              

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[codspeed-hq]

CodSpeed Performance Report

Merging #256 will not alter performance

_{Comparing fix-docs (91cf211) with main (59a37da)}

Summary

✅ 9 untouched benchmarks