[Datasets] Improve `to_tf` docstring (#29464)
[Datasets] Improve `to_tf` docstring (#29464)

The `Dataset.to_tf` docstring is out-of-date, and it doesn't contain examples. This PR updates the docstring content and adds docstring examples.

Signed-off-by: Balaji Veeramani <75f7d7e2623d1cfd50b8ac7ae8d68c4e5475bc55@berkeley.edu>
Co-authored-by: Clark Zinzow <5f3e059213ced26a35cc43fecafe1f89d235f484@gmail.com>
ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray