Document VMWare bootdisk provisioning

[lzap]

It is completely undocumented!

https://community.theforeman.org/t/ipxe-does-not-work-after-upgrading-to-2-4-1/24472

[dgoetz]

Perhaps interesting to keep in mind while doing the documentation, there is some ongoing effort to have the same feature for Proxmox: theforeman/foreman_bootdisk#90

[Lennonka]

I think that, instead of documenting every combination of compute resource and provisioning method, it would be more useful to document compute resources and provisioning methods separately and cross-link which methods can be used with particular compute resources. If it's an option to do it that way.
But until that is done, I'm keeping this issue opened.