AT-12785: Update CHANGELOG.md

https://amplify-education.atlassian.net/browse/AT-12785

Author: rddimon

CHANGELOG.md

@@ -5,13 +5,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## [4.0.0] - 2024-11-26
+## [4.0.0] - 2024-11-27
+
+### Added
+- Serverless V4 support.
 
 ### Changed
 
 - Dropped Node14.x support.
 - Dropped Serverless 2.x support.
-- Updated npm dependencies to fix security vulnerabilities
+- Updated npm dependencies to fix security vulnerabilities.
 
 ## [3.2.0] - 2024-01-08