[Train] Update saving / loading checkpoint documentation (#20973)
[Train] Update saving / loading checkpoint documentation (#20973)

This PR updates saving / loading checkpoint examples.

Co-authored-by: matthewdeng <792b5ca5a9ea149a6c3f5ccdfceb76378df01f67@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