embed the previously manually edited outdated documentation

from https://github.com/OpenRA/OpenRA/wiki/Trait-Documentation

OpenRA.Mods.RA/Valued.cs

@@ -8,21 +8,26 @@
  */
 #endregion
 
+using OpenRA.FileFormats;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA
 {
+	[Desc("How much the unit is worth.")]
 	public class ValuedInfo : TraitInfo<Valued>
 	{
+		[Desc("Used in production, but also for bounties so remember to set it > 0 even for NPCs.")]
 		public readonly int Cost = 0;
 	}
 
 	public class Valued { }
 
+	[Desc("Shown in the build palette widget.")]
 	public class TooltipInfo : ITraitInfo
 	{
 		public readonly string Description = "";
 		public readonly string Name = "";
+		[Desc("Defaults to actor name + icon suffix.")]
 		public readonly string Icon = null;
 
 		public virtual object Create(ActorInitializer init) { return new Tooltip(init.self, this); }