HDRP update changelog

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

 - When LightLayers is enabled, the AmbientOclusion is store in the GBuffer in deferred path allowing to avoid double occlusion with SSAO. In forward the double occlusion is now always avoided.
 - Added the possibility to add an override transform on the camera for volume interpolation
 - Added desired lux intensity and auto multiplier for HDRI sky
+- Added gradient sky
 
 ### Fixed
 - Fixed an issue with PreIntegratedFGD texture being sometimes destroyed and not regenerated causing rendering to break