ENHANCEMENT: Make h3 and h2 the "Site credits" title in the other set…

[MaximilianoRicoTabo]

…tings section in the level settings page

All Submissions:

• [x] Have you followed the Contributing guidelines?
• [x] Does your code follow the WordPress' coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you successfully run tests with your changes locally?

Changelog entry

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.