feat: add QubesOS comparison

[Ganwtrs]

Closes Issue #157 and addresses Issue #52

(Sorry if this is rude @EsseLowNitro cuz you self assigned this, but you said

Self-assigned just in case, I can write the FAQ item today.

and you didn’t do it that day)

[EsseLowNitro]

Sorry for the late reply, and thank you for the PR. I had written something about it in a separate branch but didn't feel like it was complete enough, since I tried to compare secureblue and Qubes OS' virtualization security while not having good enough comprehension of the pieces involved. It's not rude that you worked on solving the open issue instead.

I nit from your PR the inclusion of the section "It does not focus on virtualization, and does not involve qubes or templates whatsoever" to something more like "It does not at all aid in sharing resources between virtual machines or detaching singular apps from their guest OS, like Qubes OS does" (which afaik are cool convenience features that OS offers). Because Linux OS' are also capable of virtualization per se, and maybe this helps give a clearer picture on how the two OS' differ.