Clarify known restrictions for model updates via side inputs.

[tvalentyn]

No description provided.

[github-actions]

📋 Review Summary

This PR updates the docstring for WatchFilePattern in apache_beam.ml.inference.utils to document known restrictions around file modification timestamps and uploading multiple model updates within a single polling interval.

🔍 General Feedback

• The documentation additions accurately reflect the behavior of _GetLatestFileByTimeStamp, _ConvertIterToSingleton, and the downstream AsSingleton side-input consumption pattern.
• Formatting and numbering of the notes section are clean and consistent.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.91%. Comparing base (76f6e6d) to head (7206237).
⚠️ Report is 212 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #40600       +/-   ##
=============================================
+ Coverage     56.16%   79.91%   +23.74%     
=============================================
  Files          1124      488      -636     
  Lines        178336    82384    -95952     
  Branches       1489        0     -1489     
=============================================
- Hits         100170    65834    -34336     
+ Misses        75645    16550    -59095     
+ Partials       2521        0     -2521     

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go	?
java	?
python	79.91% <ø> (+0.35%)	⬆️

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[github-actions]

Assigning reviewers:

R: @damccorm for label python.
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[damccorm]

Thanks - this does seem like it could be fixable by looking at the timestamps and picking the latest, but this is fine for now

[tvalentyn]

Yes, might be possible, we even have logic for that but it is broken: #40638