message: Docstring typo fix: "_options" arg name -> "options".
diff: @@ -25,15 +25,16 @@ from tensorflow.python.util.tf_export import tf_export
  class CheckpointOptions(object):
  """Options for constructing a Checkpoint.
  - Used as the `_options` argument to the `tf.Checkpoint` constructor to adjust
  - how variables are saved.
  + Used as the `options` argument to either `tf.train.Checkpoint.save()` or
  + `tf.train.Checkpoint.restore()` methods to adjust how variables are
  + saved/restored.
  Example: Run IO ops on "localhost" while saving a checkpoint:
  ```
  step = tf.Variable(0, name="step")
  - checkpoint = tf.Checkpoint(step=step)
  - options = tf.CheckpointOptions(experimental_io_device="/job:localhost")
  + checkpoint = tf.train.Checkpoint(step=step)
  + options = tf.train.CheckpointOptions(experimental_io_device="/job:localhost")
  checkpoint.save("/tmp/ckpt", options=options)
  ```
  """
  