Update changelog

Author: yavorona

packages/optimizely-sdk/CHANGELOG.MD

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### New Features
+
+- Added `enabled` field to decision metadata structure to support upcoming application-controlled introduction of tracking for non-experiment Flag decisions ([#619](https://github.com/optimizely/javascript-sdk/pull/619))
+
 ## [4.4.1] - November 5, 2020
 
 ### Bug fixes