changed _pages to pages and removed include pages from config file. turned out this wasn't necessary.

pages/mydoc/mydoc_collections.md

@@ -0,0 +1,40 @@
+---
+title:  Collections
+tags: [content_types]
+keywords: groups, api, structure
+last_updated: July 3, 2016
+summary: "Collections are useful if you want to loop through a special folder of pages that you make available in a content API. You could also use collections if you have a set of articles that you want to treat differently from the other content, with a different layout or format."
+sidebar: mydoc_sidebar
+permalink: mydoc_collections.html
+folder: mydoc
+---
+
+## What are collections
+Collections are custom content types different from pages and posts. You might create a collection if you want to treat a specific set of articles in a unique way, such as with a custom layout or listing. For more detail on collections, see [Ben Balter's explanation of collections here](http://ben.balter.com/2016/02/20/jekyll-collections/).
+
+## Create a collection
+To create a collection, add the following in your configuration file:
+
+```
+collections:
+  tooltips:
+    output: true
+```
+
+In this example, "tooltips"" is the name of the collection.
+
+## Interacting with collections
+
+You can interact with collections by using the `site.collectionname` namespace, where `collectionname` is what you've configured. In this case, if I wanted to loop through all tooltips, I would use `site.tooltips` instead of `site.pages` or `site.posts`.
+
+See [Collections in the Jekyll documentation](http://jekyllrb.com/docs/collections/) for more information.
+
+## How to use collections
+
+I haven't found a huge use for collections in normal documentation. However, I did find a use for collections in generating a tooltip file that would be used for delivering tooltips to a user interface from text files in the documentation. See [Help APIs and UI tooltips][mydoc_help_api] for details.
+
+## Video tutorial on collections
+
+See this [video tutorial on Jekyll.tips](http://jekyll.tips/jekyll-casts/introduction-to-collections/) for more details on collections.
+
+{% include links.html %}