Created by: jczaja
In PaddlePaddle inplace functionality was added to oneDNN/DNNL/MKL-DNN integration. This PR is explaining its concepts.
Rendered document: https://github.com/jczaja/FluidDoc/blob/prv-mkldnn-inplace/doc/fluid/design/mkldnn/inplace/inplace.md
@luotao1 , @grygielski , @wozna , @wojtuss, @Sand3r-, @lidanqing-intel Please review