Capitalized the first letter of a sentence for correctness

CONTRIBUTING.md

@@ -66,11 +66,11 @@ file in the repository, as needed.
 You can also read and contribute to the WinUI documentation here:  
 https://docs.microsoft.com/uwp/toolkits/winui
 
-You can find usage examples of the controls available in WinUI in the Xaml Controls Gallery app:  
- https://github.com/Microsoft/Xaml-Controls-Gallery/  
+You can find usage examples of the controls available in WinUI in the WinUI 3 Gallery app:  
+ https://github.com/Microsoft/WinUI-Gallery/  
 
- which can also be installed from the Windows Store:  
- https://www.microsoft.com/p/xaml-controls-gallery/9msvh128x2zt
+ Which can also be installed from the Microsoft Store:  
+ https://apps.microsoft.com/detail/9p3jfpwwdzrc
 
  ## API spec discussions