docs: improve one preposition

[nedbat]

Describe your changes
Used a more natural English idiom.

Testing performed
I read the sentence a number of times. :D

[godlygeek]

LGTM, thanks @nedbat!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.92%. Comparing base (41248ed) to head (46eed4b).
Report is 26 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #566      +/-   ##
==========================================
+ Coverage   92.55%   92.92%   +0.37%     
==========================================
  Files          91       91              
  Lines       11304    11195     -109     
  Branches     1581     2047     +466     
==========================================
- Hits        10462    10403      -59     
+ Misses        837      792      -45     
+ Partials        5        0       -5     

Flag	Coverage Δ
cpp	92.92% <ø> (+6.98%)	⬆️
python_and_cython	92.92% <ø> (-2.80%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.