message: moved determinism desc after num_parallel_calls, clarified
diff: @@ -1774,11 +1774,6 @@ name=None))
  in general precludes the possibility of executing user-defined
  transformations in parallel (because of Python GIL).
  - The order of elements yielded by this transformation is
  - deterministic, as long as `map_func` is a pure function and
  - `deterministic=True`. If `map_func` contains any stateful operations, the
  - order in which that state is accessed is undefined.
  -
  Performance can often be improved by setting `num_parallel_calls` so that
  `map` will use multiple threads to process elements. If deterministic order
  isn't required, it can also improve performance to set
  @@ -1789,6 +1784,12 @@ name=None))
  ... num_parallel_calls=tf.data.AUTOTUNE,
  ... deterministic=False)
  + If `num_parallel_calls > 1`, the order of elements yielded by this
  + transformation is deterministic if `deterministic=True`. If `map_func`
  + contains stateful operations and `num_parallel_calls > 1`, the order in
  + which that state is accessed is undefined, so the values of output elements
  + may not be deterministic regardless of the `deterministic` flag value.
  +
  Args:
  map_func: A function mapping a dataset element to another dataset element.
  num_parallel_calls: (Optional.) A `tf.int32` scalar `tf.Tensor`,
  