make the words match the code

Author: mcabbott

src/utils.jl

@@ -446,9 +446,10 @@ randn32(dims...) = Base.randn(Float32, dims...)
 Return a bias parameter for a layer, based on the value given
 to the constructor's keyword `bias=bias`.
 
-* `bias == true` creates a zero vector, of the same type as weights.
+* `bias == true` creates a trainable array of the given size, of the same type as `weights`, initialised to zero.
 * `bias == false` returns `false` now, which is understood by AD to be non-differentiable.
-* `bias::AbstractArray` uses the array provided, provided it has the correct size and eltype. If the type is wrong, it will be converted.
+* `bias::AbstractArray` uses the array provided, provided it has the correct size.
+  It does not at present correct the `eltype` to match that of `weights`.
 """
 function create_bias(weights::AbstractArray, bias::Bool, dims::Integer...)
   bias ? fill!(similar(weights, dims...), 0) : false