add center tag

Author: igorw

source/index.html

@@ -63,7 +63,7 @@ <h2 class="text-center">Supported frameworks</h2>
     </ul>
     {% endspaceless %}
 
-    <p><a href="http://symfony.com/components/HttpKernel">See the full list on symfony.com</a></p>
+    <p class="text-center"><a href="http://symfony.com/components/HttpKernel">See the full list on symfony.com</a></p>
 </div>
 
 <hr>