Update release notes

Author: kidinov

RELEASE-NOTES.txt

@@ -2,6 +2,10 @@
 *** Use [*****] to indicate smoke tests of all critical flows should be run on the final APK before release (e.g. major library or targetSdk updates).
 *** For entries which are touching the Android Wear app's, start entry with `[WEAR]` too.
 
+23.9
+-----
+- [*][Woo POS] Fixed loading indicator colors to match the design [https://github.com/woocommerce/woocommerce-android/pull/15043]
+
 23.8
 -----
 - [*] Fixed system back button not working on Order Creation screen [https://github.com/woocommerce/woocommerce-android/pull/15016]