Add CNN to the list of examples

Author: milancurcic

README.md

@@ -173,9 +173,13 @@ to run the tests.
 The easiest way to get a sense of how to use neural-fortran is to look at
 examples, in increasing level of complexity:
 
-1. [simple](example/simple.f90): Approximating a simple, constant data relationship
+1. [simple](example/simple.f90): Approximating a simple, constant data
+  relationship
 2. [sine](example/sine.f90): Approximating a sine function
-3. [mnist](example/mnist.f90): Hand-written digit recognition using the MNIST dataset
+3. [mnist](example/mnist.f90): Hand-written digit recognition using the MNIST
+  dataset
+4. [cnn](example/cnn.f90): Creating and running forward a simple CNN using
+  `input`, `conv2d`, `maxpool2d`, `flatten`, and `dense` layers.
 
 The examples also show you the extent of the public API that's meant to be
 used in applications, i.e. anything from the `nf` module.