Update geometry.md

[stuart-fb]

Correct axis for camera flip rotation.

Pull Request Template

Summary
I think the docs mis-identify which axis is rotated around to convert between standard and flipped camera.

• Briefly describe the changes made in this pull request:
  • [Insert summary of changes]

Changes

• Describe the changes made in this pull request:
  • [Insert detailed description of changes]
  • Include relevant information about:
    • New features added
    • Bugs fixed
    • Performance improvements
    • Code refactoring

Motivation

• Explain the motivation behind making these changes:
  • [Insert motivation behind changes]

Testing

• Describe the testing performed to verify the changes:
  • [Insert testing details]
  • Include information about:
    • Test cases added or modified
    • Results of testing

Checklist

• Confirm that the following have been completed:
  • Code compiles and runs successfully on all supported platforms
  • All tests pass
  • Documentation is updated (if applicable)
  • Changes follow the project's coding standards

Additional Comments

• Any additional comments or information that may be helpful:
  • [Insert additional comments]

[facebook-github-bot]

@enpe has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[enpe]

Good find! Thanks for reporting it!

[facebook-github-bot]

@enpe merged this pull request in 56e00bb.