[NVIDIA TF] Optimize embedding_lookup_sparse using new grad op [PART 3/3]
Thanks, I've added notes to Release.md. I've also rebased and bumped the compat horizon. @cantonios are there still some internal tests failing?
Sequel to https://github.com/tensorflow/tensorflow/pull/61294

(This is a rebased version of the approved https://github.com/benbarsdell/tensorflow/pull/2)

cc @bfontain @nluehr @pjannaty