man: virsh: Mention how to disable snapshot of disk in snapshot-create-as
man: virsh: Mention how to disable snapshot of disk in snapshot-create-as

Document that --diskspec DISK,snapshot=no disables snapshot for the
given disk.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>

olafhering/libvirt,nertpinx/libvirt,nertpinx/libvirt,jardasgit/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,crobinso/libvirt,fabianfreyer/libvirt,libvirt/libvirt,libvirt/libvirt,jfehlig/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,zippy2/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,crobinso/libvirt,crobinso/libvirt,jardasgit/libvirt,nertpinx/libvirt,olafhering/libvirt,jardasgit/libvirt,crobinso/libvirt,olafhering/libvirt,zippy2/libvirt,nertpinx/libvirt