title: Override template in django admin
body: <p>I'm using Django 1.11</p>
  
  <ol>
  <li><p>I was able to extend/override one template called <code>change_form.html</code></p>
  
  <p>I placed this file under <code>/templates/admin/my_app/my_model/</code></p>
  
  <p>For this one I extended and changed one block, like in the <a href="https://docs.djangoproject.com/en/1.11/ref/contrib/admin/#overriding-vs-replacing-an-admin-template" rel="nofollow noreferrer">example</a> in django docs </p></li>
  <li><p>I was <strong>not</strong> able to override one template called <code>submit_line.html</code></p>
  
  <p>I tried placing it under <code>/templates/admin/</code>, <code>/templates/admin/my_app/</code>, and <code>/templates/admin/my_app/my_model/</code>. None worked.</p>
  
  <p>I edited the file under <code>django/contrib</code> and it worked, but I don't want to change <strong>that file</strong>. It was just to see if the content was showing. </p></li>
  </ol>
  
  <p>I just want to add one button to the template, so the user can download one XML file. </p>