Add margin input value order as a comment (#5067)

* Add margin input value order as a comment

* Make a better comment and move value to remark

Robust.Client/UserInterface/Control.Layout.cs

@@ -52,6 +52,10 @@ namespace Robust.Client.UserInterface
         [ViewVariables] public bool IsMeasureValid { get; private set; }
         [ViewVariables] public bool IsArrangeValid { get; private set; }
 
+        /// <summary>
+        /// Controls the amount of empty space in virtual pixels around the control.
+        /// </summary>
+        /// <remarks>Values can be provided as "All" or "Horizontal, Vertical" or "Left, Top, Right, Bottom"</remarks>
         [ViewVariables]
         public Thickness Margin
         {