Update DescriptionXmlBuilder.cs

Emby.Dlna/Server/DescriptionXmlBuilder.cs

@@ -256,6 +256,12 @@ namespace Emby.Dlna.Server
             builder.Append("</serviceList>");
         }
 
+        /// <summary>
+        /// Builds a valid url for inclusion in the xml.
+        /// </summary>
+        /// <param name="url">Url to include.</param>
+        /// <param name="absoluteUrl">Optional. When set to true, the absolute url is always used.</param>
+        /// <returns>The url to use for the element.</returns>
         private string BuildUrl(string url, bool absoluteUrl = false)
         {
             if (string.IsNullOrEmpty(url))