message: Fix typo in datasets docstring
diff: @@ -995,7 +995,7 @@ class Dataset(object):
  filenames = ["/var/data/file1.txt", "/var/data/file2.txt", ..."]
  dataset = (Dataset.from_tensor_slices(filenames)
  .interleave(
  - lambda x: TextLineDataset(x).map(parse_fn, num_threads=1)
  + lambda x: TextLineDataset(x).map(parse_fn, num_threads=1),
  cycle_length=4, block_length=16))
  ```
  