ARO requires 2 subnets while Azure unmanaged cluster requires 1.

We rebranded Azure as ARO in the CoCo guide because we thought they had identical requirements. Now we will have to revert the section to Azure and document ARO as a variant. This requires rewriting the introduction and updating common attributes.

For 2nd subnet, see Emanuele's user guide. This documentation will require updates to the peer pods CM module.