Updating sample references in preparation for breaking changes in the sample folders (#5403)

Switched to an existing short URL which I will update on the backend once the updated samples are published.

Author: mikebattista

hub/apps/desktop/modernize/grant-identity-to-nonpackaged-apps.md

@@ -149,8 +149,8 @@ Note the below important details about this code:
 * Set `externalLocation` to the absolute path of your application's installation directory (without any executable names)
 * Set `packagePath` to the absolute path of the identity package produced in the previous step (with the file name)
 
-For a complete example including unregistering the package on uninstall, see [`StartUp.cs`](https://github.com/microsoft/AppModelSamples/blob/0c019d835d194dfc65ee0c0663086582d48165a9/Samples/SparsePackages/PhotoStoreDemo/StartUp.cs#L146-L220).
+For production-ready code in C# and C++, see [Sample apps](#sample-apps) below. The samples also demonstrate how to unregister the identity package on uninstall.
 
-## Sample app
+## Sample apps
 
-See the [SparsePackages](https://github.com/microsoft/AppModelSamples/tree/master/Samples/SparsePackages) sample for a fully functional sample app that demonstrates how to grant package identity to a desktop app by registering an identity package.
+See the [PackageWithExternalLocation](https://aka.ms/sparsepkgsample) samples for fully functional C# and C++ apps that demonstrate how to register an identity package.