Update what's new for Parallax feature

dist/preview release/what's new.md

@@ -5,6 +5,7 @@
     - Support for shaders includes ([deltakosh](https://github.com/deltakosh))
     - new mesh type : `LineSystem` ([jerome](https://github.com/jbousquie))
     - SerializationHelper for complex classes using TypeScript decorators  ([deltakosh](https://github.com/deltakosh))
+    - StandardMaterial now supports Parallax and Parallax Occlusion Mapping ([nockawa](https://github.com/nockawa))
   - **Updates**
     - New OnPickTrigger support for spritesManager ([deltakosh](https://github.com/deltakosh))
     - New SPS method `digest()` ([jerome](https://github.com/jbousquie))