Improve error message missing region

[davide-f]

What does this PR do?

Closes #32

Type of Change

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Chore (refactoring code or workflow improvements)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] This change requires a documentation update

Checklist

Simple documentation improvement but I added eo.view_regions() feature as eo is the main module. Let me know your thoughts.

[pz-max]

@davide-f , guess ready to merge?

[davide-f]

Yes