Added news and removed type annotation from SkipConnection structure

NEWS.md

@@ -1,5 +1,6 @@
 # v0.9.0
 * [Depthwise convolutional 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.
+* New [SkipConnection](https://github.com/FluxML/Flux.jl/pull/446), which can be used to train residual neural network architectures.
 
 # v0.8.0
 

src/layers/basic.jl

@@ -190,26 +190,29 @@ function (mo::Maxout)(input::AbstractArray)
     mapreduce(f -> f(input), (acc, out) -> max.(acc, out), mo.over)
 end
 
-
 """
     SkipConnection(layers...)
 
-
 Creates a Skip Connection, which constitutes of a layer or Chain of consecutive layers
 and a shortcut connection linking the input to the block to the
-output through a user-supplied function.
+output through a user-supplied callable.
 
 `SkipConnection` requires the output dimension to be the same as the input.
+
+A 'ResNet'-type skip-connection with identity shortcut would simply be
+```julia
+    SkipConnection(layer, (a,b) -> a + b)
+```
 """
 
 struct SkipConnection
   layers
-  connection::Function  #user can pass arbitrary connections here, such as `.+`
+  connection  #user can pass arbitrary connections here, such as (a,b) -> a + b
 end
 
 @treelike SkipConnection
 
-function (skip::SkipConnection)(input::AbstractArray)
+function (skip::SkipConnection)(input)
   #We apply the layers to the input and return the result of the application of the layers and the original input
   skip.connection(skip.layers(input), input)
 end