Update docs page to reflect correct hypervisors

[sandisamp]

Currently the documentation states the following description on the home page.

This project automates the User-Provisioned Infrastructure (UPI) method for deploying Red Hat OpenShift Container Platform (RHOCP) on IBM zSystems / LinuxONE using Kernel-based Virtual Machine (KVM) as the hypervisor.

This is misleading as this repositories support more hypervisors and installation methods. This should be correctly reflected by updating this. Possibly as a matrix which would be helpful to the unfamiliar users.