Created by: jczaja

This is the same as #1132 , but I could not reopen so new PR was created.

This is first in a series of documents describing architecture of mkl-dnn integration. It is meant to be useful for PaddlePaddle developers and mkl-dnn integration maintainers in particular.

Rendered(suitable for reading) version of document can be seen at: https://github.com/jczaja/Paddle/blob/prv-mkldnn-doc-data-transformation/paddle/fluid/operators/mkldnn/doc/data_transformation/data_transform.md

@grygielski , @bingyanghuang Please review