Add comment about padding update computation

osu.Game.Rulesets.Taiko/UI/TaikoPlayfield.cs

@@ -164,6 +164,8 @@ namespace osu.Game.Rulesets.Taiko.UI
         {
             base.Update();
 
+            // Padding is required to be updated for elements which are based on "absolute" X sized elements.
+            // This is basically allowing for correct alignment as relative pieces move around them.
             rightArea.Padding = new MarginPadding { Left = leftArea.DrawWidth };
             hitTargetOffsetContent.Padding = new MarginPadding { Left = HitTarget.DrawWidth / 2 };
         }