bump version in config and datestamp release notes

Author: Dottenpixel

RELEASENOTES.general.md

@@ -1,7 +1,7 @@
 <!-- Release notes authoring guidelines: http://keepachangelog.com/ -->
 <!-- On release, add general notes here. In time the legacy release notes will be add to this -->
 
-## 2.15.9 - Upcoming
+## 2.15.9 - July 16, 2021
 
 - Added SLDS scope customizer tool: `npm run slds:customizer`
 

ui/_config.scss

@@ -9,7 +9,7 @@
 ///
 /// @type String
 /// @access private
-$app-version: "2.15.8";
+$app-version: "2.15.9";
 
 /// Debug mode (uncomment to activate)
 /// Turn on to output deprecation warnings during development