codeninjasuk.github.io/_includes/documents-collection.html

{% assign entries = site[include.collection] %}

{% if include.sort_by %}
  {% assign entries = entries | sort: include.sort_by %}
{% endif %}

{% if include.sort_order == 'reverse' %}
  {% assign entries = entries | reverse %}
{% endif %}

{%- for post in entries -%}
  {%- unless post.hidden -%}
    {% include archive-single.html %}
  {%- endunless -%}
{%- endfor -%}