Add some comments

osu.Game.Rulesets.Catch/UI/Catcher.cs

@@ -92,6 +92,9 @@ public CatcherAnimationState CurrentState
             private set => Body.AnimationState.Value = value;
         }
 
+        /// <summary>
+        /// Whether the catcher is currently dashing.
+        /// </summary>
         public bool Dashing { get; set; }
 
         /// <summary>

osu.Game.Rulesets.Catch/UI/CatcherTrailDisplay.cs

@@ -17,6 +17,10 @@ namespace osu.Game.Rulesets.Catch.UI
     /// </summary>
     public class CatcherTrailDisplay : CompositeDrawable
     {
+        /// <summary>
+        /// The most recent dash trail added in this container.
+        /// Only alive (not faded out) trails are considered.
+        /// </summary>
         [CanBeNull]
         public CatcherTrail LastDashTrail => dashTrails.Concat(hyperDashTrails)
                                                        .OrderByDescending(trail => trail.LifetimeStart)