Add image documentation

[ryantwolf]

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Description

This PR adds

• [x] Docstrings for all classes in the image curation
• [ ] API docs for the docstrings
• [ ] Pages in the user guide about image curation
• [ ] Updated README with image curation

Usage

N/A

Checklist

• [ ] I am familiar with the Contributing Guide.
• [ ] New or Existing tests cover these changes.
• [ ] The documentation is up to date with these changes.