_includes/latest-posts-list.html

<h3>Latest {{ page.categories | first | replace: '-',' ' | capitalize }}</h3>
<ul>
{% capture category_name %}{{ page.categories | first }}{% endcapture %}
{% for post in site.categories.[category_name] limit:3 %}
  <li><a href="{{ site.url }}{{ post.url }}">{{ post.title }}</a></li>
{% endfor %}
</ul>