website/_includes/menu.html

{% assign sorted_nodes = site.pages | sort:"menutitle" | sort:"menuorder" %}
{%- for node in sorted_nodes -%}
{%- if node.lang == page.lang and node.menutitle -%}
<li>
  <a href="{{ node.url }}" {%- if node.url == page.url %} class="is-active"{% endif -%}>
    {{ node.menutitle | escape }}
  </a>
</li>
{%- endif -%}
{%- endfor -%}
{% for link in site.external %}
<li><a href="{{ link.url }}">{{ link.name }}</a></li>
{% endfor %}