docs: Add field descriptions to Actor models

[apify-service-account]

• Updates the auto-generated Pydantic models and TypedDicts based on the proposed OpenAPI specification changes.
• Based on apify-docs PR #2841.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.69%. Comparing base (064b5cc) to head (06e4e3b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #989      +/-   ##
==========================================
+ Coverage   94.63%   94.69%   +0.06%     
==========================================
  Files          58       58              
  Lines        5259     5301      +42     
==========================================
+ Hits         4977     5020      +43     
+ Misses        282      281       -1     

Flag	Coverage Δ
integration	92.47% <100.00%> (+0.34%)	⬆️
unit	84.17% <100.00%> (+0.12%)	⬆️

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