Do not show empty languages menu if there are no translations for the page

Signed-off-by: Alexander Borsuk <me@alex.bio>

templates/language_selector.html

@@ -6,7 +6,9 @@
     }
   </script>
   <!-- Hidden checkbox is used for pure CSS toggle menu. -->
+  {% if resource.translations | length > 1 %}
   <input type="checkbox" id="lang-menu-trigger" class="lang-menu-trigger" />
+  {% endif %}
   <label class="no-print" for="lang-menu-trigger">
      🌐 {{ lang | upper }}
   </label>