docs: clarify MaskAnnotator mask requirements

[tarunbommawar27]

Before submitting

• Self-reviewed the code
• Updated documentation, follow [Google-style](https://google.github.io/styleguide/pyguide.html#383-functions-and-methods)
• Added docs entry for autogeneration (if new functions/classes)
• Added/updated tests
• All tests pass locally

Description

Clarifies the expected input format for MaskAnnotator in the annotators documentation.

This PR adds a short note explaining that MaskAnnotator expects instance segmentation masks in detections.mask, and that each mask should match the height and width of the image passed to annotate.

Type of Change

• 📝 Documentation update

Motivation and Context

The existing MaskAnnotator example shows how to annotate detections, but it does not explicitly explain what mask format is expected. This can be confusing for new users, especially when converting predictions from model-specific outputs.

This documentation update makes the expected detections.mask input clearer and points users toward common conversion methods such as sv.Detections.from_ultralytics(...) and sv.Detections.from_inference(...).

No linked issue.

Changes Made

• Added a note under the MaskAnnotator example
• Clarified that detections.mask should contain instance segmentation masks
• Mentioned common conversion paths for framework-specific model outputs

Testing

• I have tested this code locally
• I have added unit tests that prove my fix is effective or that my feature works
• All new and existing tests pass

Commands run:

uv run pre-commit run --files docs/detection/annotators.md
python - <<'PY'
import supervision as sv
print("supervision import OK:", sv.__version__)
PY

Also ran the full test suite locally earlier:

uv run pytest tests -q --maxfail=1

Result:

1751 passed

Google Colab (optional)

Not applicable for this documentation-only change.

Screenshots/Videos (optional)

Not applicable.

Additional Notes

This is a small documentation-only contribution intended to improve clarity for users working with segmentation masks.

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

Documentation-only change to clarify what MaskAnnotator expects in detections.mask, helping users supply correctly-shaped instance segmentation masks (or convert from common model outputs) when using the annotators docs.

Changes:

• Added an admonition note under the MaskAnnotator example describing expected mask input and common conversion entry points.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79%. Comparing base (918b613) to head (7bfddcd).

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2279   +/-   ##
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  Coverage       79%     79%           
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  Files           66      66           
  Lines         8567    8567           
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  Hits          6726    6726           
  Misses        1841    1841           

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