Add missing reference to language_data.js in search.html

sphinx_mer_rtd_theme/search.html

@@ -12,6 +12,7 @@
 {%- block scripts %}
     {{ super() }}
     <script type="text/javascript" src="{{ pathto('_static/searchtools.js', 1) }}"></script>
+    <script type="text/javascript" src="_static/language_data.js"></script>
 {%- endblock %}
 {% block footer %}
   <script type="text/javascript">