Fix a broken link in `Threading and Queues` docs (#14160)
Fix a broken link in `Threading and Queues` docs (#14160)

The link to Datasets in `Threading and Queues` seems
to be broken. This fix attempts to fix the broken link.

Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>
tensorflow/docs,tensorflow/docs,tensorflow/docs,tensorflow/docs-l10n