Polish implementation and documentation

[defagos]

Description

This PR proposes a few minor implementation and documentation improvements found randomly when looking at the code.

Changes made

• Fix documentation issues.
• Remove the Internal folder that was not contributing much to the project structure.
• Improve CommandersActService.start(with:) implementation to avoid early return. The optional binding is an artifact of lacking nullability in Commanders Act headers, we should never skip what's next. We could also replace the optional binding with a force unwrap in this case but there is not much to gain IMHO.
• Improve code consistency.

Checklist

• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).