[ue4] 4.0 changelog update: added ue4 line to 4.0 section as well.

CHANGELOG.md

@@ -33,6 +33,7 @@
 ### UE4
 * `SpineWidget` now supports the full widget transform, including rendering scale/shear.
 * Materials on `SkeletonRendererComponent` are now blueprint read and writeable. This allows setting dynamic material instances at runtime.
+* Added `InitialSkin` property to `USpineWidget`. This allows previewing different skins in the UMG Designer. Initial skins can still be overridden via blueprint events such as `On Initialized`.
 * **Breaking changes**: `SpineWidget` no longer has the `Scale` property. Instead the size x/y properties can be used.
 
 ## C# ##