Update nvidia gpu operator docs

[manuelbuil]

Update the NVIDIA GPU operator docs with:

• v26.3.1 information
• Specify that now the operator can also manage driver and library installation on any operating system: Provide the SLES 16.0 example
• As "pre-installation of drivers" will now be not that common, hide the steps to verify it was done properly and remove one of the last checks "kubectl get node $NODENAME -o jsonpath='{.metadata.labels}' | grep "nvidia.com/gpu.deploy.driver""