Updated change log (#179)

Updated the change log to add a known issue with 3d bbox and skinned mesh renderers

Author: StevenBorkman

com.unity.perception/CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 Before upgrading a project to this version of the Perception package, make sure to keep a record of **all sampler ranges** in your added Randomizers. Due to a change in how sampler ranges are serialized, **after upgrading to this version, ranges for all stock Perception samplers (Uniform and Normal Samplers) will be reset**, and will need to be manually reverted by the user.
 
+### Known Issues
+
+The bounding box 3D labeler does not work with labeled assets that utilize a skinned mesh renderer. These are commonly used with animated models.
+
 ### Added
 
 Added keypoint ground truth labeling