[DOC]: Improve cub::DeviceTransform documentation

### Is this a duplicate?

- [x] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this bug and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Is this for new documentation, or an update to existing docs?

Update

### Describe the incorrect/future/missing documentation

`cub::DeviceTransform` is not listed on the landing page of cub's device-wide primitives [here](https://nvidia.github.io/cccl/cub/api_docs/device_wide.html).

Additionally, we should add a note to use `cuda::proclaim_copyable_arguments` with `cub::DeviceTransform` when possible to enable the TMA code path.

### If this is a correction, please provide a link to the incorrect documentation. If this is a new documentation request, please link to where you have looked.

https://nvidia.github.io/cccl/cub/api_docs/device_wide.html -> should list cub::DeviceTransform
https://nvidia.github.io/cccl/cub/api/structcub_1_1DeviceTransform.html#cub-devicetransform -> add note about `cuda::proclaim_copyable_arguments`.