message: Further updates to the docs of tf.distribute.get_replica_context.
diff: @@ -106,7 +106,8 @@ def get_replica_context():
  Most `tf.distribute.Strategy` methods may only be executed in
  a cross-replica context, in a replica context you should use the
  - API of the `ReplicaContext` object returned by this method instead.
  + API of the `tf.distribute.ReplicaContext` object returned by this
  + method instead.
  ```
  assert tf.distribute.get_replica_context() is not None # default
  @@ -114,14 +115,17 @@ def get_replica_context():
  assert tf.distribute.get_replica_context() is None
  def f():
  - assert tf.distribute.get_replica_context() is not None # for strategy
  + replica_context = tf.distribute.get_replica_context() # for strategy
  + assert replica_context is not None
  + tf.print("Replica id: ", replica_context.replica_id_in_sync_group,
  + " of ", replica_context.num_replicas_in_sync)
  strategy.experimental_run_v2(f)
  ```
  Returns:
  - The current `ReplicaContext` object when in a replica context scope,
  - else `None`.
  + The current `tf.distribute.ReplicaContext` object when in a replica context
  + scope, else `None`.
  Within a particular block, exactly one of these two things will be true:
  