Add NEWS.md entry for #756

Author: staticfloat

NEWS.md

@@ -1,3 +1,6 @@
+# v0.9.0
+* [Depthwise comvolutional layer API changes](https://github.com/FluxML/Flux.jl/pull/756) from `in => mult` channel specification to `in => out` channel specification, and deprecates implicit `out` constructor.
+
 # v0.8.0
 
 * New [ConvTranspose layer](https://github.com/FluxML/Flux.jl/pull/311).