Clarify OCP and support options

[mikemckiernan]

Address some feedback:

• Update the intro page to include OCP in the title and at the bottom of the page to direct NVAIE customers to NVIDIA support and others to Red Hat support.
• Add OCP into the title for these pages to orient the reader:
  • Prereqs
  • Inst and Upg Overview
  • Inst NFD
  • Inst GPU Op

[github-actions]

Documentation preview

https://nvidia.github.io/cloud-native-docs/review/pr-109

[mikemckiernan]

@francisguillier, no rush on my part, but PTAL when you get a chance.

[francisguillier]

thanks Mike. These changes look good to me.

1 request that NVEX team emitted was to create a shortcut in the standard GPU operator page (https://docs.nvidia.com/datacenter/cloud-native/gpu-operator/latest/getting-started.html)
that would redirect to the OpenShift GPU operator page (https://docs.nvidia.com/datacenter/cloud-native/openshift/latest/index.html)

One of the reason was customer went to the first page and then installed GPU operator using Helm commands on an OpenShift cluster.
If the customer was aware there is an another procedure to deploy GPU operator on OpenShift, they would not commit this mistake.