Merge #1062

1062: docstring ensure signature code formatting r=CarloLucibello a=visr

by using a four space indent instead of two

Fixes issues seen here:

![image](https://user-images.githubusercontent.com/4471859/75627427-54aa6600-5bd0-11ea-93d3-92901d44db59.png)

Where the type signature has no code formatting, and a code block is introduced that throws off the rest of the formatting.

Co-authored-by: Martijn Visser <mgvisser@gmail.com>

src/data/iris.jl

@@ -28,7 +28,6 @@ function load()
 end
 
 """
-
     labels()
 
 Get the labels of the iris dataset, a 150 element array of strings listing the
@@ -53,7 +52,6 @@ function labels()
 end
 
 """
-
     features()
 
 Get the features of the iris dataset.  This is a 4x150 matrix of Float64

src/optimise/optimisers.jl

@@ -444,14 +444,13 @@ end
     InvDecay(γ)
 
 Applies inverse time decay to an optimiser, i.e., the effective step size at iteration `n` is `eta / (1 + γ * n)` where `eta` is the initial step size. The wrapped optimiser's step size is not modified.
-```
 
 ## Parameters
   - gamma (γ): Defaults to `0.001`
 
 ## Example
 ```julia
-  Optimiser(InvDecay(..), Opt(..))
+Optimiser(InvDecay(..), Opt(..))
 ```
 """
 mutable struct InvDecay
@@ -483,9 +482,8 @@ Discount the learning rate `eta` by a multiplicative factor `decay` every `decay
 ## Example
 To apply exponential decay to an optimiser:
 ```julia
-  Optimiser(ExpDecay(..), Opt(..))
-
-  opt = Optimiser(ExpDecay(), ADAM())
+Optimiser(ExpDecay(..), Opt(..))
+opt = Optimiser(ExpDecay(), ADAM())
 ```
 """
 mutable struct ExpDecay