Add what's new entry

dist/preview release/what's new.md

@@ -44,6 +44,7 @@
 - Added `Color3.toHSV()`, `Color3.toHSVToRef()` and `Color3.HSVtoRGBToRef()` ([Deltakosh](https://github.com/deltakosh/))
 - Added `ShadowGenerator.onAfterShadowMapRenderObservable` and `ShadowGenerator.onAfterShadowMapMeshRenderObservable` ([Deltakosh](https://github.com/deltakosh/))
 - Added support for side by side and top bottom images in the `PhotoDome` ([Deltakosh](https://github.com/deltakosh/))
+- Added playground ts-local (TypeScript support for local playground) ([pjoe](https://github.com/pjoe/))
 
 ### Meshes
 - Added new CreateTiledPlane and CreateTiledBox ([JohnK](https://github.com/BabylonJSGuide/))