docker-docs/_includes/treebuilder.html

{% assign topicFound="false" %}
{% for section in site.data.toc.horizontalnav %}
  {% assign activeCSS = "" %}
  {% if topicFound=="false" %}
    {% assign tree = site.data.toc[section.node] %}
    {% capture thisSection %}{% include tree.html %}{% endcapture %}
    {% if section.path == page.url or thisSection contains "active currentPage" %}
      {% capture leftnav %}{{ thisSection }}{% endcapture %}
      {% capture activeCSS %} class="active"{% endcapture %}
      {% assign topicFound="true" %}
    {% endif %}
  {% endif %}
  <li id="{{ section.node }}"{{ activeCSS }}><a href="{{ section.path }}">{{ section.title }}</a></li>
{% endfor %}