virsh: clarify snapshot --live
virsh: clarify snapshot --live

In libvirt, snapshot means disk snapshot.
snapshot --live is more like VM checkpoint.
Make it clear in virsh.pod.

Signed-off-by: Chen Hanxiao <818f8a165c25fa146ecad28e2ef3e3fb996fa364@gmail.com>
Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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