Given this YAML:
- maincategory:
title: \"Projects\"
subcategory:
title: \"General\"
item:
title: \"Alpha\"
item:
- title: "Projects"
subcategories:
- title: "project-sub1"
items:
- title: "project-sub1-item1"
href: "#"
- title: "project-sub1-item2"
href: "#"
- title: "project-sub2"
items:
- title: "project-sub2-item1"
href: "#"
- title: "project-sub2-item2"
href: "#"
- title: "Support"
subcategories:
- title: "support-sub1"
items:
- title: "support-sub1-item1"
href: "#"
- title: "support-sub1-item2"
href: "#"
{% for entry in site.data.entries %}
<h2>{{ entry.title }}</h2>
{% for subcategory in entry.subcategories %}
<h3>{{ subcategory.title }}</h3>
<ul>
{% for item in subcategory.items %}
<li><a href="{{ item.href }}">{{ item.title }}</a></li>
{% endfor %}
</ul>
{% endfor %}
{% endfor %}
<h2>Projects</h3>
<h3>project-sub1</h3>
<ul>
<li><a href="#">project-sub1-item1</a></li>
<li><a href="#">project-sub1-item2</a></li>
</ul>
<h3>project-sub2</h3>
<ul>
<li><a href="#">project-sub2-item1</a></li>
<li><a href="#">project-sub2-item2</a></li>
</ul>
<h2>Support</h3>
<h3>support-sub1</h3>
<ul>
<li><a href="#">support-sub1-item1</a></li>
<li><a href="#">support-sub1-item2</a></li>
</ul>