Updated changelog with known issues section

Author: sleal-unity

com.unity.perception/CHANGELOG.md

@@ -19,6 +19,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [0.5.0-preview.1] - 2020-10-14
 
+### Known Issues
+
+Creating a new 2020.1.x project and adding the perception package to the project causes a memory error that is a [known issue in 2020.1 editors](https://issuetracker.unity3d.com/issues/wild-memory-leaks-leading-to-stackallocator-walkallocations-crashes). Users can remedy this issue by closing and reopening the editor.
+
 ### Added
 
 Added Randomizers and RandomizerTags