Replace XAML Controls Gallery to WinUI 3 Gallery in readme (#316)

Co-authored-by: Bob Pulliam <[email protected]>

Author: Mysterious-Dev

README.md

@@ -35,7 +35,7 @@ This repository hosts samples for the [Windows App SDK](https://github.com/micro
 #### User Interface and Input
 - [Windowing](Samples/Windowing): This sample demonstrates how to manage app windows using the Windowing APIs.
 - [Windows Input and Composition Gallery](https://github.com/microsoft/WindowsCompositionSamples): This collection of samples showcases Microsoft.UI.Composition and Microsoft.UI.Input APIs.
-- [XAML Controls Gallery](https://github.com/microsoft/Xaml-Controls-Gallery/tree/winui3): This is a sample app that showcases all of the WinUI 3 controls in action.
+- [WinUI 3 Gallery](https://github.com/microsoft/WinUI-Gallery/): This is a sample app that showcases all of the WinUI 3 controls in action.
 
 ## Requirements