fix misisng close tag

_includes/default-footer.html

@@ -5,6 +5,6 @@
             provides researchers with online training materials, connects them with local trainers, and helps promoting open data analysis practices worldwide.
         </p>
         {% include _includes/license.html %}
-        <p>This is revision <a href="https://github.com/galaxyproject/training-material/commit/{{ site.git_revision }}">{{ site.git_revision }}</p>
+        <p>This is revision <a href="https://github.com/galaxyproject/training-material/commit/{{ site.git_revision }}">{{ site.git_revision }}</a></p>
     </div>
 </footer>