added avg pooling to readme
added avg pooling to readme

monikajhuria/cuda-convnet2.torch-master_update,monikajhuria/cuda-convnet2.torch-master_update,monikajhuria/cuda-convnet2.torch-master_update,szagoruyko/cuda-convnet2.torch,szagoruyko/cuda-convnet2.torch,szagoruyko/cuda-convnet2.torch,szagoruyko/cuda-convnet2.torch,soumith/cuda-convnet2.torch,soumith/cuda-convnet2.torch,soumith/cuda-convnet2.torch