borg/docs/_templates/globaltoc.html

<div class="sidebar-block">
  <div class="sidebar-toc">
    {# Restrict the sidebar toc depth to two levels while generating command usage pages.
       This avoids superfluous entries for each "Description" and "Examples" heading. #}
    {% if pagename.startswith("usage/") and pagename not in (
      "usage/general", "usage/help", "usage/debug", "usage/notes",
    ) %}
      {% set maxdepth = 2 %}
    {% else %}
      {% set maxdepth = 3 %}
    {% endif %}

    {% set toctree = toctree(maxdepth=maxdepth, collapse=True) %}
    {% if toctree %}
      {{ toctree }}
    {% else %}
      {{ toc }}
    {% endif %}
  </div>
</div>