Fix mismatched GPU docker image in the doc. (pytorch#5319)

docs/gpu.md

@@ -18,7 +18,7 @@ curl -s -L https://nvidia.github.io/nvidia-docker/gpgkey | sudo apt-key add -
 curl -s -L https://nvidia.github.io/nvidia-docker/$distribution/nvidia-docker.list | sudo tee /etc/apt/sources.list.d/nvidia-docker.list
 sudo apt-get update && sudo apt-get install -y nvidia-container-toolkit
 sudo systemctl restart docker
-sudo docker run --gpus all -it -d gcr.io/tpu-pytorch/xla:nightly_3.7\8_cuda_11.2 bin/bash
+sudo docker run --gpus all -it -d us-central1-docker.pkg.dev/tpu-pytorch-releases/docker/xla:nightly_3.8_cuda_11.7 bin/bash
 sudo docker exec -it $(sudo docker ps | awk 'NR==2 { print $1 }') /bin/bash
 ```