[Docs] DCGM on GKE

[asaiacai]

Right now drivers and container runtimes require the gpu-operator. However, this requires using Ubuntu based nodes which don't support high performance networking on GKE. We should have an installation guide for DCGM exporter specific to GKE so we can run on ContainerOS instead so we can use TCPX

This is a good starting point.
https://cloud.google.com/stackdriver/docs/managed-prometheus/exporters/nvidia-dcgm