fix(button-group): added requested changes in the changelog

Author: georgianastasov

CHANGELOG.md

@@ -6,7 +6,7 @@ All notable changes for each version of this project will be documented in this
 
 ### General
 - `IgxButtonGroup`:
-    - Reverted cancellable on `selected` and `deselected` events (added in 15.1.0) as it was breaking firing order.
+    - Reverted cancellable on `selected` and `deselected` events (added in 15.1.24) as it was breaking firing order and related handling.
 
 ## 15.1.0