message: Fix a typo in tf.distribute.Strategy.reduce docstring
diff: @@ -1321,7 +1321,7 @@ class StrategyBase(object):
  reduce_op: a `tf.distribute.ReduceOp` value specifying how values should
  be combined. Allows using string representation of the enum such as
  "SUM", "MEAN".
  - value: a `tf.distribute.DistributeValues` instance, e.g. returned by
  + value: a `tf.distribute.DistributedValues` instance, e.g. returned by
  `Strategy.run`, to be combined into a single tensor. It can also be a
  regular tensor when used with `OneDeviceStrategy` or default strategy.
  axis: specifies the dimension to reduce along within each
  