Update CHANGELOG.txt

CHANGELOG.txt

@@ -9,8 +9,8 @@ Changelog
  * Removed the "More" section from the admin menu
  * Added pagination to page listings in admin
  * Support for setting a subpage_types property on page models, to define which page types are allowed as subpages
- * Added a new datetime picker
- * Added styleguide
+ * Added a new datetime picker widget
+ * Added styleguide (mainly for wagtail developers)
  * Aesthetic improvements to preview experience
  * Fix: Animated GIFs are now coalesced before resizing
  * Fix: Wand backend clones images before modifying them