Update release notes for 1.1.0

Author: jswift

RELEASE_NOTES.md

@@ -1,10 +1,3 @@
 ### New Features
 
-Adding support for the Widget/Content endpoints. See the [Widgets Tutorial](https://developer.bigcommerce.com/api-docs/store-management/widgets/tutorials/tutorial)
-for usage.
-
-Implemented:
-- [Widgets API](https://developer.bigcommerce.com/api-reference/store-management/widgets/widget/createwidget)
-- [Widget Templates](https://developer.bigcommerce.com/api-reference/store-management/widgets/widget-template/createwidgettemplate)
-- Get Theme Regions
-- [Placements API](https://developer.bigcommerce.com/api-reference/store-management/widgets/placement/getplacements)
+Implemented create and update Product Variant as this has been missed previously.