message: Improve documentation of deterministic flag.
  Add note that deterministic flag is True by default
  More-complete explanation
diff: @@ -71,8 +71,10 @@ The `tf.data` Python API creates instances of this op from
  `Dataset.interleave()` when the `num_parallel_calls` parameter of that method
  is set to any value other than `None`.
  -If the `experimental_deterministic` parameter of `tf.data.Options` is set to
  -`True`, then the output of this op will be deterministic. Otherwise the output
  -may be nondeterministic.
  +By default, the output of this dataset will be deterministic, which may result
  +in the dataset blocking if the next data item to be returned isn't available.
  +In order to avoid head-of-line blocking, one can set the
  +`experimental_deterministic` parameter of `tf.data.Options` to `False`,
  +which can improve performance at the expense of non-determinism.
  END
  }
  