Added some TODOs

samples/SkiaSharpSample.FormsSample/SkiaSharpSample.FormsSample/DetailContentsPage.xaml

@@ -4,6 +4,7 @@
              xmlns:views="clr-namespace:SkiaSharp.Views.Forms;assembly=SkiaSharp.Views.Forms"
              x:Class="SkiaSharpSample.FormsSample.DetailContentsPage">
   <views:SKView x:Name="canvas" PaintSurface="OnPaintSample">
+    <!-- TODO: for some reason this does not work on iOS -->
     <views:SKView.GestureRecognizers>
       <TapGestureRecognizer Tapped="OnTapSample" />
     </views:SKView.GestureRecognizers>

samples/SkiaSharpSample.FormsSample/SkiaSharpSample.FormsSample/DetailContentsPage.xaml.cs

@@ -33,6 +33,8 @@ namespace SkiaSharpSample.FormsSample
 
 		public void SwitchBackend(SampleBackends backend)
 		{
+			// TODO: implement once the Forms GL is working
+
 			DisplayAlert("Configure Backend", "This functionality is not yet implemented.", "OK");
 		}