docs: Clarify unprivileged sgio feature
docs: Clarify unprivileged sgio feature

Update the descriptions for disk and hostdev sgio in order to indicate
not all hypervisors and OS's support this feature

Signed-off-by: John Ferlan <87558058f6f829e5ec976c8ef960720af4ff9c7d@redhat.com>

libvirt/libvirt,agx/libvirt,jardasgit/libvirt,zippy2/libvirt,jardasgit/libvirt,zippy2/libvirt,datto/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,crobinso/libvirt,rlaager/libvirt,fabianfreyer/libvirt,rlaager/libvirt,VenkatDatta/libvirt,eskultety/libvirt,jfehlig/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,olafhering/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,olafhering/libvirt,datto/libvirt,rlaager/libvirt,jardasgit/libvirt,crobinso/libvirt,libvirt/libvirt,agx/libvirt,VenkatDatta/libvirt,datto/libvirt,agx/libvirt,libvirt/libvirt,eskultety/libvirt,datto/libvirt,zippy2/libvirt,andreabolognani/libvirt,olafhering/libvirt,eskultety/libvirt,crobinso/libvirt,datto/libvirt,libvirt/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,rlaager/libvirt,rlaager/libvirt,taget/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,andreabolognani/libvirt,taget/libvirt,taget/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jfehlig/libvirt,taget/libvirt,agx/libvirt,jardasgit/libvirt,jfehlig/libvirt,andreabolognani/libvirt,zippy2/libvirt,taget/libvirt,agx/libvirt,andreabolognani/libvirt,eskultety/libvirt,eskultety/libvirt,nertpinx/libvirt,crobinso/libvirt