Update CHANGELOG.md

Author: cicirello

CHANGELOG.md

@@ -4,11 +4,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased] - 2023-04-07
+## [Unreleased] - 2023-04-13
 
 ### Added
 
 ### Changed
+* Permutation now caches hash on first call to hashCode() to optimize applications that rely heavily on hashing.
 
 ### Deprecated