using cuda enabled pytorch image

**What did you find confusing? Please describe.**
kindly tell what is the dockerfile format in order to use cuda/gpu on sagemaker instance, i heard we have to use sagemaker-inference-toolkit , i tried using simple cuda image but its having problem serving
**Describe how documentation can be improved**
there was no examples/samples related to building image with cuda support
**Additional context**
Add any other context or screenshots about the documentation request here.

No file, test, or documentation entry point is named. Start by reading the repository documentation and the linked Deep Learning Containers Dockerfiles, then identify where a CUDA-enabled PyTorch image example belongs; done means users have a documented Dockerfile example and serving guidance for SageMaker GPU instances.

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