Fix docs typo about aggregate

[sfc-gh-dhuang]

Description

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Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
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[!IMPORTANT] Fixes typos in documentation by changing aggregation function to numpy.mean and updating context specification.

• Documentation Fixes:
  • Corrects aggregation function from numpy.min to numpy.mean in feedback_aggregation.md, with_app.md, and README.md.
  • Updates context specification from statement to context in feedback_aggregation.md and README.md.

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