lguest: lguest.txt documentation fix

Mention the config options for the Virtio drivers and move the Virtualization
menu to the toplevel.

Signed-off-by: Paul Bolle <[e-mail]>
Signed-off-by: Rusty Russell <[e-mail]>

Documentation/lguest/lguest.txt

···
          CONFIG_PHYSICAL_ALIGN=0x100000)
 
   "Device Drivers":
+     "Block devices"
+        "Virtio block driver (EXPERIMENTAL)" = M/Y
      "Network device support"
         "Universal TUN/TAP device driver support" = M/Y
-           (CONFIG_TUN=m)
-     "Virtualization"
-        "Linux hypervisor example code" = M/Y
-           (CONFIG_LGUEST=m)
+        "Virtio network driver (EXPERIMENTAL)" = M/Y
+           (CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m and CONFIG_TUN=m)
+
+  "Virtualization"
+     "Linux hypervisor example code" = M/Y
+        (CONFIG_LGUEST=m)
 
 - A tool called "lguest" is available in this directory: type "make"
   to build it.  If you didn't build your kernel in-tree, use "make