site: HTML fix

site/index.html

@@ -550,7 +550,7 @@ <h2>Demos, presentations &amp; publications</h2>
             <ul>
                 <li><a href="assets/stam.webm">This screencast video</a> (no audio) shows <strong>stam-tools</strong>, the command-line tools for STAM</li>
                 <li><a href="https://nbviewer.org/github/annotation/stam-python/blob/master/tutorial.ipynb">Python tutorial "Standoff Text Annotation for Pythonistas"</a> is a tutorial for <strong>stam-python</strong> in the form of an interactive jupyter notebook.</li>
-                <li><a href="https://raw.githubusercontent.com/annotation/stam/master/docs/poster.pdf">Poster</li>
+                <li><a href="https://raw.githubusercontent.com/annotation/stam/master/docs/poster.pdf">Poster</a></li>
             </ul>
         </div>
     </section>