Update CHANGELOG.md

Author: keveleigh

org.mixedrealitytoolkit.core/CHANGELOG.md

@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Added
 
-* Added support for moving the MRTK.Generated folder around the project's Assets folder structure instead of enforcing a root location.
+* Added support for moving the MRTK.Generated folder around the project's Assets folder structure instead of enforcing a root location. [PR #969](https://github.com/MixedRealityToolkit/MixedRealityToolkit-Unity/pull/969)
 
 ### Fixed