Fix docstring. (#1305)

This is breaking everything below it.

https://www.tensorflow.org/io/api_docs/python/tfio/experimental/IODataset

Author: MarkDaoust

tensorflow_io/core/python/experimental/io_dataset_ops.py

@@ -171,7 +171,7 @@ def from_numpy_file(cls, filename, spec=None, **kwargs):
         In case numpy file consists of unnamed elements, a tuple of numpy
         arrays are returned, otherwise a dict is returned for named
         elements.
-        ```
+
         Args:
           filename: filename of numpy file (npy or npz).
           spec: A tuple of tf.TensorSpec or dtype, or a dict of