message: Add link to RFC from raw_ops
diff: @@ -139,6 +139,13 @@ else:
  ```
  """
  +tf.raw_ops.__doc__ += """
  +
  +Note: `tf.raw_ops` provides direct/low level access to all TensorFlow ops. See \
  +[the RFC](https://github.com/tensorflow/community/blob/master/rfcs/20181225-tf-raw-ops.md)
  +for details. Unless you are library writer, you likely do not need to use these
  +ops directly.
  +"""
  # The doc generator isn't aware of tf_export.
  # So prefix the score tuples with -1 when this is the canonical name, +1
  