Add PanelBody for InspectorControls

[mitogh]

Using PanelBody in the InspectorControls and example helps to get the styles and according styles out of the box.

Description

Updates on doc examples.

How has this been tested?

This is a doc update.

Screenshots

Types of changes

Documentation update

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[jorgefilipecosta]

LGTM 👍 I'm getting a crash when pasting the code in the console but it also happens on the trunk so it is another issue that should be addressed in a different PR.