Amend whatsnew for 2D array texture support

dist/preview release/what's new.md

@@ -41,6 +41,7 @@
 - Added optional parameter to use Euler angles in planeRotationGizmo ([CedricGuillemet](https://github.com/CedricGuillemet))
 - Added `AnimationGroup.onAnimationGroupLoopObservable` ([Deltakosh](https://github.com/deltakosh/))
 - Supports custom materials to generate glow through ```referenceMeshToUseItsOwnMaterial``` in the ```GlowLayer``` ([sebavan](http://www.github.com/sebavan))
+- Added `RawTexture2DArray` to enable use of WebGL2 2D array textures by custom shaders ([atg](https://github.com/atg))
 
 ### Engine