Modified files
templates/app/article_update.html
                    --- 
+++ 
@@ -2,6 +2,7 @@
 {% block content %}
   <h1>Edit Article</h1>
+  <p>Last edited on {{ article.updated_at | date:"jS F Y" }}</p>
   <form method="POST">
     {% csrf_token %}
     {{ form.as_p }}