[DOC]: Document how to use CCCL from the CTK in a cmake project

### 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?

New

### Describe the incorrect/future/missing documentation

I am a CCCL user who is using cmake and I want to use CCCL provided by the CTK. I would like to know what the recommended best practice is on how to do this.

This issue can be closed when we've added a section under the ["CUDA Toolkit" section ](https://github.com/NVIDIA/cccl?tab=readme-ov-file#cuda-toolkit) that describes how what cmake commands I should use to make the `CCCL::CCCL` cmake target available provided by the CCCL headers found from the CTK.

### 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.

_No response_