Update XML docs

Author: Sergio0694

components/Media/src/Brushes/AcrylicBrush.cs

@@ -69,10 +69,16 @@ private static void OnSourcePropertyChanged(DependencyObject d, DependencyProper
     }
 #endif
 
+#if WINUI2
     /// <summary>
     /// Gets or sets the blur amount for the effect (must be a positive value)
     /// </summary>
     /// <remarks>This property is ignored when the active mode is <see cref="AcrylicBackgroundSource.HostBackdrop"/></remarks>
+#else
+    /// <summary>
+    /// Gets or sets the blur amount for the effect (must be a positive value)
+    /// </summary>
+#endif
     public double BlurAmount
     {
         get => (double)GetValue(BlurAmountProperty);