Add _data sub-folder support to docs

site/docs/datafiles.md

@@ -61,3 +61,47 @@ You can now render the list of members in a template:
 </ul>
 {% endraw %}
 {% endhighlight %}
+
+## Example: Organizations
+
+Data files can also be placed in sub-folders of the `_data` folder. Each folder level will be added to a variable's namespace. The example bellow shows how GitHub organizations could be defined separately in a file under the `orgs` folder:
+
+In `_data/orgs/jekyll.yml`:
+
+{% highlight yaml %}
+username: jekyll
+name: Jekyll
+members:
+  - name: Tom Preston-Werner
+    github: mojombo
+
+  - name: Parker Moore
+    github: parkr
+{% endhighlight %}
+
+In `_data/orgs/doeorg.yml`:
+
+{% highlight yaml %}
+username: doeorg
+name: Doe Org
+members:
+  - name: John Doe
+    github: jdoe
+{% endhighlight %}
+
+The organizations can then be accessed via `site.data.orgs`, followed by the file name:
+
+{% highlight html %}
+{% raw %}
+<ul>
+{% for org in site.data.orgs %}
+  <li>
+    <a href="https://github.com/{{ org.username }}">
+      {{ org.name }}
+    </a>
+    ({{ org.members | size }} members)
+  </li>
+{% endfor %}
+</ul>
+{% endraw %}
+{% endhighlight %}