correct code examples in box_utils docstring (#4572)
correct code examples in box_utils docstring (#4572)

* clean up code examle in box_utils docstring

Signed-off-by: Can Zhao <4846a130ae9485ad00dceef3ead1cc7b334112aa@nvidia.com>

* clean up code examle in box_utils docstring

Signed-off-by: Can Zhao <4846a130ae9485ad00dceef3ead1cc7b334112aa@nvidia.com>
Project-MONAI/MONAI,Project-MONAI/MONAI,Project-MONAI/MONAI,Project-MONAI/MONAI