Add notes about collections

site/collections/notes.php

@@ -1,5 +1,11 @@
 <?php
-
+/**
+ * Collections help with keeping your code DRY 
+ * if you need to reuse the same set up pages, files or users in multiple places across your site.
+ * 
+ * More about collections:
+ * http://getkirby.test/docs/guide/templates/collections
+ */
 return function () {
     return page('notes')
         ->children()