Make the set property ApiDescription.ResponseDescription public

Author: Tasteful

src/System.Web.Http/Description/ApiDescription.cs

@@ -82,7 +82,7 @@ public ApiDescription()
         /// <summary>
         /// Gets the response description.
         /// </summary>
-        public ResponseDescription ResponseDescription { get; internal set; }
+        public ResponseDescription ResponseDescription { get; set; }
 
         /// <summary>
         /// Gets the ID. The ID is unique within <see cref="HttpServer"/>.