Add docs

1. Loosen type constraints on `inputscale`
2. Updated README

Author: theabhirath

README.md

@@ -20,6 +20,8 @@
 | [ResNet](https://arxiv.org/abs/1512.03385)       | [`ResNet`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.ResNet.html)           | N            |
 | [GoogLeNet](https://arxiv.org/abs/1409.4842)     | [`GoogLeNet`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.GoogLeNet.html)     | N            |
 | [Inception-v3](https://arxiv.org/abs/1512.00567) | [`Inceptionv3`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.Inceptionv3.html)   | N            |
+| [Inception-v4](https://arxiv.org/abs/1602.07261) | [`Inceptionv4`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.Inceptionv4.html)   | N            |
+| [InceptionResNet-v2](https://arxiv.org/abs/1602.07261) | [`Inceptionv3`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.InceptionResNetv2.html)   | N            |
 | [SqueezeNet](https://arxiv.org/abs/1602.07360)   | [`SqueezeNet`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.SqueezeNet.html)   | N            |
 | [DenseNet](https://arxiv.org/abs/1608.06993)     | [`DenseNet`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.DenseNet.html)       | N            |
 | [ResNeXt](https://arxiv.org/abs/1611.05431)      | [`ResNeXt`](https://fluxml.ai/Metalhead.jl/dev/docstrings/Metalhead.ResNeXt.html)         | N            |

src/convnets/inception.jl

@@ -286,6 +286,15 @@ end
 
 """
     inceptionv4(; inchannels = 3, dropout = 0.0, nclasses = 1000)
+
+Create an Inceptionv4 model.
+([reference](https://arxiv.org/abs/1602.07261))
+
+# Arguments
+
+  - inchannels: number of input channels.
+  - dropout: rate of dropout in classifier head.
+  - nclasses: the number of output classes.
 """
 function inceptionv4(; inchannels = 3, dropout = 0.0, nclasses = 1000)
     body = Chain(conv_bn((3, 3), inchannels, 32; stride = 2)...,
@@ -314,6 +323,18 @@ function inceptionv4(; inchannels = 3, dropout = 0.0, nclasses = 1000)
     return Chain(body, head)
 end
 
+"""
+    Inceptionv4(; inchannels = 3, dropout = 0.0, nclasses = 1000)
+
+Creates an Inceptionv4 model.
+([reference](https://arxiv.org/abs/1602.07261))
+
+# Arguments
+
+  - inchannels: number of input channels.
+  - dropout: rate of dropout in classifier head.
+  - nclasses: the number of output classes.
+"""
 struct Inceptionv4
     layers::Any
 end
@@ -398,6 +419,18 @@ function block8(scale = 1.0f0; no_relu = false)
                                 branch3, inputscale(scale; activation = activation)), +)
 end
 
+"""
+    inceptionresnetv2(; inchannels = 3, dropout = 0.0, nclasses = 1000)
+
+Creates an InceptionResNetv2 model.
+([reference](https://arxiv.org/abs/1602.07261))
+
+# Arguments
+
+  - inchannels: number of input channels.
+  - dropout: rate of dropout in classifier head.
+  - nclasses: the number of output classes.
+"""
 function inceptionresnetv2(; inchannels = 3, dropout = 0.0, nclasses = 1000)
     body = Chain(conv_bn((3, 3), inchannels, 32; stride = 2)...,
                  conv_bn((3, 3), 32, 32)...,
@@ -418,6 +451,18 @@ function inceptionresnetv2(; inchannels = 3, dropout = 0.0, nclasses = 1000)
     return Chain(body, head)
 end
 
+"""
+    InceptionResNetv2(; inchannels = 3, dropout = 0.0, nclasses = 1000)
+
+Creates an InceptionResNetv2 model.
+([reference](https://arxiv.org/abs/1602.07261))
+
+# Arguments
+
+  - inchannels: number of input channels.
+  - dropout: rate of dropout in classifier head.
+  - nclasses: the number of output classes.
+"""
 struct InceptionResNetv2
     layers::Any
 end

src/utilities.jl

@@ -39,12 +39,12 @@ cat_channels(xy...) = cat(xy...; dims = Val(3))
 """
     inputscale(λ; activation = identity)
 
-Scale the input (assumed to be an `AbstractArray`) by a scalar λ and applies an activation
-function to it. Equivalent to `activation.(λ .* x)`.
+Scale the input by a scalar λ and applies an activation function to it.
+Equivalent to `activation.(λ .* x)`.
 """
 inputscale(λ; activation = identity) = x -> _input_scale(x, λ, activation)
-_input_scale(x::AbstractArray, λ, activation) = activation.(λ .* x)
-_input_scale(x::AbstractArray, λ, ::typeof(identity)) = λ .* x
+_input_scale(x, λ, activation) = activation.(λ .* x)
+_input_scale(x, λ, ::typeof(identity)) = λ .* x
 
 """
     swapdims(perm)