Adopt terminology consistent with Qubes OS documentation ("qube" vs "VM")

[ChumOfChance]

At some point recently, Qubes OS switched from "VM" terminology ("AppVM", "Template", "NetVM", etc) to more user-friendly "qube" terminology ("app qube", "template", "net qube"). These changes are summarized in the Qubes OS documentation glossary. The glossary even defines usage of the terms, in somewhat of a style guide.

I think it makes sense to keep the SDW docs aligned with the terminology used by Qubes OS in its own documentation/tools. These terms are reflected in Qubes OS itself, e.g. in the Qubes OS Global Config tool.

As far as I can tell the main point of discussion for this change was here: QubesOS/qubes-issues#1015

I'm sure @deeplow has thoughts.

[deeplow]

It may make sense to make the switch. It's been a long time in the works, but I still see a few references here and there. I'll try to check on this topic during the weekend.

[deeplow]

I checked on this during the summit. The respective issue was closed because it had been changed in the majority of places. So it should be OK for us to do the switch. If we ever find "VM" mentions, they are "bugs" and we're free to flag / fix them.