Added missing XMLDoc for LastModified property

Author: JeremyCaney

OnTopic.ViewModels/TopicViewModel.cs

@@ -70,6 +70,12 @@ public class TopicViewModel: ITopicViewModel {
     /// <inheritdoc />
     public bool IsHidden { get; set; }
 
+    /*==========================================================================================================================
+    | LAST MODIFIED
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   The date that the topic was last modified on.
+    /// </summary>
     public DateTime LastModified { get; set; }
 
     /*==========================================================================================================================