Update whats new

dist/preview release/what's new.md

@@ -97,6 +97,7 @@
 - AMD "define" declaration is no longer anonymous ([RaananW](https://github.com/RaananW))
 - Collision worker didn't initialize instanced meshes correctly - [#3819](https://github.com/BabylonJS/Babylon.js/issues/3819) ([RaananW](https://github.com/RaananW))
 - postMessage calls in webworkers were fixed ([RaananW](https://github.com/RaananW))
+- fixed WebCam Texture on Firefox and Edge - [#3825](https://github.com/BabylonJS/Babylon.js/issues/3825) ([sebavan](https://github.com/sebavan))
 
 ## Breaking changes