Update YAML export description in docs

[apainintheneck]

Checklist

• I have read the contributing doc.
• I have included a link to the relevant issue number.
• I have checked to ensure there aren't other open pull requests
  for the same issue.
• I have written new tests for these changes, as needed.

Updates the YAML export example to be more realistic. The previous one threw an error because it was an unsupported use case.

Closes #1525.

[wren]

Thank you!