Add page taxonomy links for tags and categories

- Customizable text via _data file
- Enable/disable links by setting archive page filenames in _config.yml

_pages/portfolio-archive.html

@@ -9,7 +9,7 @@ permalink: /portfolio/
 
 {% for category in group_names %}
   {% assign posts = group_items[forloop.index0] %}
-  <h2 class="archive__subtitle">{{ category }}</h2>
+  <h2 id="{{ category | slugify }}" class="archive__subtitle">{{ category }}</h2>
   {% for post in posts %}
     {% include archive-list-single.html %}
   {% endfor %}