Update v1.6.0 release notes

Author: dotMorten

src/WinUIEx/WinUIEx.csproj

@@ -25,6 +25,8 @@
         - Added Backdrop support to SplashScreen.
         - Added WindowEx.ZOrderChanged event.
         - Added new virtual members to WindowEx to react to position, presenter and zorder changes with a simple override.
+        - Improved DPI changed handling.
+        - Fixed a bug in persistance restore when restoring window position to a screen with a different DPI.
     </PackageReleaseNotes>
   </PropertyGroup>