better walkthrough README
better walkthrough README

The default batch_size for transformer_base_single_gpu
has been decreased to 2048 in transform.py
(it used to be 4096 I think).
So if it is too much, the user must use a smaller value.

tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,rsepassi/tensor2tensor,waterblue13/tensor2tensor,vthorsteinsson/tensor2tensor,rsepassi/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,waterblue13/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,waterblue13/tensor2tensor,rsepassi/tensor2tensor,rsepassi/tensor2tensor