docs: expand on dualboot posibilites and what we can assure.

This probably needs expanding on both upstream and Fedora/CentOS docs. 
During CentOS Connect @alexiri raised that it was hard to find a guide/supported status for dual booting on bootc systems. With the advent of Asahi Linux on Macs and the prevalence of Windows we should probably document what is possible, supported and what if any are the limitations.