image_to_vm: suggest the use of cros_vm

Replace the outdated recommended command to start the VM. Don't use
'kvm', use chromite's 'cros_vm' instead.

BUG=chromium:782664
TEST=check that the suggested command line is correct.

Change-Id: I95b4e544b1d2d9c4d763747d910d54da562aaaa7
Reviewed-on: https://chromium-review.googlesource.com/889408
Commit-Ready: Achuith Bhandarkar <achuith@chromium.org>
Tested-by: Nicolas Norvez <norvez@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
1 file changed