update news

Author: CarloLucibello

NEWS.md

@@ -1,5 +1,14 @@
 # Flux Release Notes
 
+## v0.12.4
+* Implemented an [`Embedding layer`](https://github.com/FluxML/Flux.jl/pull/1516) 
+  based on recently added  `NNlib.gather` and `NNlib.scatter`.
+
+## v0.12.1 - v0.12.3
+
+* CUDA.jl 3.0 support
+* Bug fixes and optimizations.
+
 ## v0.12.0
 
 * Add [identity_init](https://github.com/FluxML/Flux.jl/pull/1524).