Merge pull request #1576 from Unity-Technologies/UpdateChangelogPCSS

Updated changelogs for PCSS

com.unity.render-pipelines.core/CHANGELOG.md

 
 ## [Unreleased]
 
+### Added
+- Add PCSS shadow filter
+
 ### Improvements
 - Improved volume UI & styling
 

com.unity.render-pipelines.high-definition/CHANGELOG.md

 ### Added
 - Add option supportDitheringCrossFade on HDRP Asset to allow to remove shader variant during player build if needed
 - Add contact shadows for punctual lights (in additional shadow settings), only one light is allowed to cast contact shadows at the same time and so at each frame a dominant light is choosed among all light with contact shadows enabled.
+- Add PCSS shadow filter support (from SRP Core)
 
 ### Changed
 - Re-enable shadow mask mode in debug view