message: TensorFlow Lite: Modernize custom operator documentation.
  Some API has been disabled/renamed even in TF1.
diff: @@ -35,9 +35,9 @@ Example:
  session = tf.compat.v1.Session()
  - graphdef_to_convert = tf.lite.convert_op_hints_to_stubs(session)
  + graphdef_to_convert = tf.lite.experimental.convert_op_hints_to_stubs(session)
  tflite_graph = tf.compat.v1.lite.toco_convert(
  - graphdef_to_convert, [image], [output])
  + graphdef_to_convert, [image], [output], allow_custom_ops=True)
  with open("/tmp/graph.fb", "wb") as fp:
  fp.write(tflite_graph)
  @@ -60,7 +60,9 @@ Once you have built your whole tensorflow graph, you can run it and train it
  as usual, but after you have done that, you need to convert the graph into
  a form that replaces these subgraphs wrapped in identities to stub ops. These
  ops don't actually exist in the normal TensorFlow runtime, but will be
  -understood by toco later.
  +understood by toco later. The generated TensorFlow Lite flatbuffer file will
  +contain a custom operator called "cool_activation". Developer needs to implement
  +and register this operator in TensorFlow Lite in order to do inference.
  """
  # TODO(aselle): Make this use generic graph transformations.
  