message: Add back link to TensorFlow Serving.
diff: @@ -7,4 +7,9 @@ the following documents:
  a cluster of TensorFlow servers.
  * @{$hadoop$How to run TensorFlow on Hadoop}, which has a highly
  self-explanatory title.
  -
  + * The entire document set for [TensorFlow serving](/serving), an open-source,
  + flexible, high-performance serving system for machine-learned models
  + designed for production environments. TensorFlow Serving provides
  + out-of-the-box integration with TensorFlow models.
  + [Source code for TensorFlow Serving](https://github.com/tensorflow/serving)
  + is available on Github.
  