Add doctests in upsample.jl

Author: Saransh-cpp

src/layers/upsample.jl

@@ -75,9 +75,41 @@ end
 """
     PixelShuffle(r::Int)
 
-Pixel shuffling layer with upscale factor `r`.
+Pixel shuffling layer with upscale factor `r`. Usually used for generating higher
+resolution images while upscaling them.
  
 See [`NNlib.pixel_shuffle`](@ref).
+
+# Examples
+```jldoctest; filter = r"[+-]?([0-9]*[.])?[0-9]+"
+julia> p = PixelShuffle(2);
+
+julia> xs = rand(2, 2, 4, 1)  # an image with 4 channels having 2X2 pixels in each channel
+2×2×4×1 Array{Float64, 4}:
+[:, :, 1, 1] =
+ 0.826452   0.0519244
+ 0.0686387  0.438346
+
+[:, :, 2, 1] =
+ 0.343179  0.445101
+ 0.543927  0.740905
+
+[:, :, 3, 1] =
+ 0.105997  0.422996
+ 0.32957   0.167205
+
+[:, :, 4, 1] =
+ 0.825737  0.98609
+ 0.757365  0.294784
+
+julia> p(xs)  # an image with only 1 channel with 4X4 pixels in the single channel
+4×4×1×1 Array{Float64, 4}:
+[:, :, 1, 1] =
+ 0.826452   0.105997  0.0519244  0.422996
+ 0.343179   0.825737  0.445101   0.98609
+ 0.0686387  0.32957   0.438346   0.167205
+ 0.543927   0.757365  0.740905   0.294784
+```
 """
 struct PixelShuffle 
   r::Int