Update clean part of the example doc

[skycastlelily]

Pull Request Checklist

• [ ] implement the feature
• [ ] write the documentation
• [ ] extend the test coverage
• [ ] update the specification
• [ ] adjust plugin docstring
• [ ] modify the json schema
• [ ] mention the version
• [ ] include a release note

[skycastlelily]

This is really a tiny merge request, which is pretty safe to be merged directly:)