Improve NavigationView documentation

Hello,

I’ve been exploring the Fluent UI library and found it to be very useful. However, I’ve encountered some difficulties understanding how navigation works, specifically with the PaneItem component.

In the current examples, it’s not clear how to navigate or change the displayed content when a PaneItem is clicked. This makes it challenging for new users to understand how to use this component for navigation purposes.

It would be greatly beneficial if the examples could be expanded to clearly demonstrate this functionality. For instance, a simple example showing how to change the displayed content when a PaneItem is clicked would be very helpful.

Additionally, more comprehensive tutorials or guides on how to use the library would be greatly appreciated. This would make it easier for developers to get started with Fluent UI and fully leverage its capabilities.

Thank you for your attention to this matter.

Start by locating the existing NavigationView examples and PaneItem documentation. Reproduce the current example, then expand it with a simple flow showing how clicking a PaneItem changes the displayed content and add clearer getting-started guidance. Done means a new user can understand and follow the navigation example without further explanation.

Written by the indexing model from the issue text.