Add an alert in taskDetail for overdue events

tasks/templates/tasks/taskDetail.djhtml

@@ -12,7 +12,11 @@
   </nav>
 
   <p> Next scheduled time: {{ task.next_recurrence|date }} </p>
-  <p> Overdue: {{ task.is_overdue }} </p>
+  {% if task.is_overdue %}
+    <div class="alert alert-danger">
+      Task is overdue!
+    </div>
+  {% endif %}
 
   <form method="post">
     {% csrf_token %}