message: [tf.data] fix the example in DispatchServer docstring
diff: @@ -88,7 +88,8 @@ class DispatchServer(object):
  >>> dispatcher = tf.data.experimental.service.DispatchServer()
  >>> dispatcher_address = dispatcher.target.split("://")[1]
  - >>> worker = tf.data.experimental.service.WorkerServer(WorkerConfig(
  + >>> worker = tf.data.experimental.service.WorkerServer(
  + ... tf.data.experimental.service.WorkerConfig(
  ... dispatcher_address=dispatcher_address))
  >>> dataset = tf.data.Dataset.range(10)
  >>> dataset = dataset.apply(tf.data.experimental.service.distribute(
  