Update changelog

Author: yavorona

packages/optimizely-sdk/CHANGELOG.MD

@@ -6,6 +6,7 @@ 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).
 
 ## [Unreleased]
+-  Refactored TypeScript type definitions to have `OptimizelyOptions` imported from `shared_types` to provide isolation from internal modules ([#629](https://github.com/optimizely/javascript-sdk/pull/629))
 
 ## [4.4.2] - November 19, 2020