Fix typos in PyROS CardinalitySet documentation

[shermanjasonaf]

Summary/Motivation:

Following up on #3969, this PR fixes typos in the PyROS CardinalitySet documentation.

AI-Use Disclosure

• AI tools were NOT used during the preparation of this PR

Notes for reviewers (optional):

Legal Acknowledgement

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.14%. Comparing base (bf99cde) to head (9bb5221).
⚠️ Report is 117 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3972      +/-   ##
==========================================
+ Coverage   90.12%   90.14%   +0.01%     
==========================================
  Files         909      917       +8     
  Lines      108582   109161     +579     
==========================================
+ Hits        97857    98400     +543     
- Misses      10725    10761      +36     

Flag	Coverage Δ
builders	29.10% <ø> (-0.01%)	⬇️
default	86.11% <ø> (ø)
expensive	35.12% <ø> (ø)
linux	87.65% <ø> (+0.02%)	⬆️
linux_other	87.65% <ø> (+0.02%)	⬆️
oldsolvers	28.04% <ø> (ø)
osx	83.10% <ø> (+0.04%)	⬆️
win	85.41% <ø> (+0.02%)	⬆️

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