Enhance Samples for better clarity

[morning4coffe-dev]

What would you like to be added:

Improve some of the Samples to provide more indications, context, or comments to the user on what is the control supposed to do. A great example of this is the WinUI Gallery which provides the user with better clarity on the available options.

WinUI Gallery examples

A description for CheckBox

Descriptions for NavigationView

Why is this needed:

Provide the user with more clarity on what is the control they are looking at.

Anything else we need to know?

Part of an internal discussion.