update comments

EduNetworkBuilder/PersonClass.cs

@@ -18,6 +18,9 @@ namespace EduNetworkBuilder
         /// The username of the person.  Will be used as a filename.  Cannot be changed once it is set
         /// </summary>
         public string UserName { get { return _UserName; } }
+        /// <summary>
+        /// The filename, without the path, of the file.  UserName + ".enbu"
+        /// </summary>
         public string FileName { get { return UserName + ".enbu"; } }
 
         /// <summary>