Create navigation.html

docs/_includes/navigation.html

@@ -0,0 +1,11 @@
+<h2>Table of contents</h2>
+{% assign mydocs = site.pages | where:"lang","en" | where:"layout","page" | group_by: 'category' | sort: 'name' %}
+{% for cat in mydocs %}
+<h3>{{ cat.name | capitalize }}</h3>
+    <ul>
+      {% assign items = cat.items | sort: 'title' %}
+      {% for item in items %}
+        <li><a href="{{ site.baseurl }}{{ item.url }}">{{ item.title }}</a></li>
+      {% endfor %}
+    </ul>
+{% endfor %}