message: Fix grammar in MirroredStrategy docstring
diff: @@ -432,7 +432,7 @@ class MirroredStrategy(distribute_lib.Strategy):
  devices: a list of device strings. If `None`, all available GPUs are used.
  If no GPUs are found, CPU is used.
  cross_device_ops: optional, a descedant of `CrossDeviceOps`. If this is not
  - set, nccl will be use by default.
  + set, nccl will be used by default.
  """
  def __init__(self, devices=None, cross_device_ops=None):
  