Update changelogs for the last terrain PR.

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

 
 ## [3.4.0-preview]
 
+### Added
+- Added a new TerrainLit shader that supports rendering of Unity terrains.
+
 ### Fixed
 - Fixed an issue where sometimes the deferred shadow texture would not be valid, causing wrong rendering.
 

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

 - When you have enabled Gizmos, they now appear correctly in the Game view.
 - Added requiresDepthPrepass field to RenderingData struct to tell if the runtime platform requires a depth prepass to generate a camera depth texture.
 - The _RenderingData_ struct now holds a reference to _CullResults_.
+- Enabled instancing on the terrain shader.
 ### Changed
 - The _RenderingData_ struct is now read-only.
 - _ScriptableRenderer_ always perform a Clear before calling _IRendererSetup::Setup_.