message: Remove reference to contrib in tensorflow/java/README
diff: > *WARNING*: The TensorFlow Java API is not currently covered by the TensorFlow
  > [API stability guarantees](https://www.tensorflow.org/guide/version_compat).
  >
  -> For using TensorFlow on Android refer instead to
  -> [contrib/android](https://www.tensorflow.org/code/tensorflow/contrib/android),
  -> [makefile](https://www.tensorflow.org/code/tensorflow/contrib/makefile#android)
  -> and/or the
  -> [Android demo](https://www.tensorflow.org/code/tensorflow/examples/android).
  +> For using TensorFlow on Android refer instead to [TensorFlow Lite](https://www.tensorflow.org/code/tensorflow/lite/).
  ## Quickstart
  