message: Correct typo and better doc.
diff: @@ -556,8 +556,8 @@ class InfeedQueue(object):
  """Generates the host-side Ops to enqueue the shards of a tuple.
  sharded_inputs is a list, one for each shard, of lists of
  - Tensors. sharded_inputs[0] is the tuple of Tensors to use to feed
  - shard 0 if the queue. Returns the host-side Ops that must be run to
  + Tensors. sharded_inputs[i] is the tuple of Tensors to use to feed
  + shard i of the queue. Returns the host-side Ops that must be run to
  enqueue the sharded tuple. The Op for shard i is colocated with the inputs
  for shard i.
  