message: Updates doc in `MirroredStrategy` now that `MultiWorkerMirroredStrategy` is available.
diff: @@ -342,7 +342,8 @@ class MirroredStrategy(distribute_lib.Strategy):
  This strategy uses one replica per device and sync replication for its
  multi-GPU version.
  - The multi-worker version will be added in the future.
  + To use `MirroredStrategy` with multiple workers, please refer to
  + `tf.distribute.MultiWorkerMirroredStrategy`.
  Args:
  devices: a list of device strings. If `None`, all available GPUs are used.
  