message: Add a note that the replica_id_in_sync_group might not correspond to XLA replica ID.
diff: @@ -2030,6 +2030,9 @@ class ReplicaContext(object):
  This identifies the replica that is part of a sync group. Currently we
  assume that all sync groups contain the same number of replicas. The value
  of the replica id can range from 0 to `num_replica_in_sync` - 1.
  +
  + NOTE: This is not guaranteed to be the same ID as the XLA replica ID use
  + for low-level operations such as collective_permute.
  """
  require_replica_context(self)
  return self._replica_id_in_sync_group
  