Documentation for sliding windows 

Created a page which describes usage of sliding windows (library/tensor/nnet/neighbours.html). 
Rephrase the first sentence. Give a little bit more explanation on what the step means (maybe give an example by saying what would happen if the step was 1 or what would happen if it was larger than neib_shape). Also, what's the format of the neib_step parameter? Any restrictions on the values in neib_step?