[DOC]: Fix dynamic shared memory reference link

### 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

There are a few remaining `//! example_block_reduce_dyn_smem.cu` in block radix and merge sort which should be updated to sphinx references.

### 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/classcub_1_1BlockRadixSort.html#classcub_1_1blockradixsort