Merge pull request #1931 from bghgary/patch-2

Update what's new.md

dist/preview release/what's new.md

@@ -44,6 +44,7 @@
 - Added Scene.DoubleClickDelay to set the timing within a double click event like PointerEventTypes.POINTERDOUBLETAP or ActionManager.OnDoublePickTrigger has to be processed ([yuccai](https://github.com/yuccai))
 - New material: `ShadowOnlyMaterial` to display shadows on transparent surfaces ([deltakosh](https://github.com/deltakosh)) 
 - Added `VertexBuffer.TangentKind` to specify tangents in place of shader-calculated tangents ([dewadswo](https://github.com/dewadswo), [bghgary](https://github.com/bghgary))
+- Added `material.twoSidedLighting` to PBRMaterial and StandardMaterial to enable flipping normals when backfaceCulling is false ([BeardedGnome](https://github.com/BeardedGnome), [bghgary](https://github.com/bghgary))
  
 ### Bug fixes
 - Fixed a bug with spotlight direction ([deltakosh](https://github.com/deltakosh))