Add closing html tag

docs/patterns/templateinheritance.rst

@@ -36,6 +36,7 @@ document that you might use for a simple two-column page. It's the job of
           {% endblock %}
         </div>
       </body>
+    </html>
 
 In this example, the ``{% block %}`` tags define four blocks that child templates
 can fill in. All the `block` tag does is tell the template engine that a