Fix HTML5 compliancy issue

templates/_header.twig

@@ -22,7 +22,7 @@
                                 <ul class="pure-menu-list">
                                 {% for key, lang in languageBar -%}
                                     {% if key == currentLanguage -%}
-                                    <a class="pure-menu-heading" href="#">{{ lang.name }}</a>
+                                    <li><a class="pure-menu-heading" href="#">{{ lang.name }}</a><li>
                                     {% else -%}
                                     {% if lang.url -%}
                                     <li class="pure-menu-item"><a href="{{ lang.url }}{%- spaceless %}