Documentation/typo in dim_order documentation

[alanocallaghan]

Description

Sorry if this is trivial, but when I notice them I feel obliged to report.

Pull request recommendations:

• [x] Name your pull request your-development-type/short-description. Ex: feature/read-tiff-files
• [x] Link to any relevant issue in the PR description. Ex: Resolves [gh-], adds tiff file format support
• [x] Provide relevant tests for your feature or bug fix.
• [x] Provide or update documentation for any feature added by your pull request.

Thanks for contributing!