add tensorflow in practice specialization in more info section

PiperOrigin-RevId: 256237862

Updated README for s390x Stable release.

Updated README for s390x Nightly artifacts.
We are working on release artifacts and will do PR for release artifacts soon.

See https://github.com/tensorflow/community/issues/28

Added an Oxford comma to line 28, to be consistent with the rest of the file.

This got really big all of a sudden.

adds links to cpu artifiacts for nightly and release builds
Replaces "IBM ppc64le" with "Linux ppc64le"
Uses the build of every commit for build status and not the nightly artifact build.
  - This last change is also made to the GPU build in this commit

Fix sentence structure

whl files for tensorflow_gpu..._ppc6le are now hosted on the OSU
Jenkins build server. Nightly builds and Stable Release builds
are provided. I didn't include the version number so we won't need
to update the readme file for every new release

PiperOrigin-RevId: 214437695

Fixed #17850

PiperOrigin-RevId: 211166112

[Intel MKL] Intel(R) Optimizations for TensorFlow* 1.10.0 has been released. Updating README.md with TensorFlow 1.10.0 links for Intel(R) MKL-DNN

PiperOrigin-RevId: 208110979