Overview

In the layout for the post we can use the variables page.next and page.previous to link to the chronological next and previous posts.

...
<nav class="post_navigation">
  {% if page.previous.url %}
    <a href="{{ page.previous.url }}">&laquo; {{ page.previous.title }}</a>
  {% endif %}
  {% if page.next.url %}
    <a href="{{ page.next.url }}">{{ page.next.title }} &raquo;</a>
  {% endif %}
</nav>
...