Release v0.6.6

[jtherrmann]

Changes at https://hyp3-docs.asf.alaska.edu/hyp3-docs/guides/insar_product_guide/#processing-options-and-optional-files look good.

[github-actions[bot]]

Developer checklist

• [x] Indicated the level of changes to this package by affixing one of these labels:
  • major -- Major changes to the API that may break current workflows
  • minor -- Minor changes to the API that do not break current workflows
  • patch -- Patches and bugfixes for the current version that do not break current workflows
  • bumpless -- Changes to documentation, CI/CD pipelines, etc. that don't affect the software's version
• [ ] (If applicable) Updated the dependencies and indicated any downstream changes that are required
• [x] Added/updated documentation for these changes
• [ ] Added/updated tests for these changes

Reviewer checklist

• [ ] Have all dependencies been updated?
• [ ] Is the level of changes labeled appropriately?
• [ ] Are all the changes described appropriately in CHANGELOG.md?
• [ ] Has the documentation been adequately updated?
• [ ] Are the tests adequate?