selfdefined/11ty/_includes/components/table-of-content.njk

<section>
  <nav class="" aria-label="Definitions">
    <ol class="multi-column u-no-padding-left list">
    {% for section in collections.tableOfContent %}
      <li>
        <span class="sub-headline">{{ section.title }}</span>
        <ol>
          {% for definition in section.definitions %}
            {% include 'components/table-of-content-item.njk' %}
          {% endfor %}
        </ol>
      </li>
    {% endfor %}
    </ol>
  </nav>
</section>