Subchapters are not Shown

[ilyaigpetrov]

If we have article and subarticles (chapter and subchapters) I offer to render all up to one level deep.
In the theme code I found:

<div class="list-group">
{% for article in part.articles %}
  {% if article.path != readme.file.path %}
  <a href="{{ article.path|resolveFile }}" class="list-group-item">
    <i class="fa fa-file-o" aria-hidden="true"></i> {{ article.title }}
  </a>
  {% endif %}
{% endfor %}
</div>

But for some reason this code doesn't work and subchapters are not rendered.
Possible result (with very bad design):

You may even go more than one level deep it will be even better to have a wider choice.