tools: Reduce table width in virsh(1)

The table included in the sample output for 'list --title' is
unnecessarily wide, which causes man to complain:

  warning [p 8, 0.5i]: can't break line

Make the table narrower.

Spotted by Lintian (manpage-has-errors-from-man tag).
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

tools/virsh.pod

@@ -546,7 +546,7 @@ Example:
 
 B<virsh> list --title
   Id    Name        State      Title
- --------------------------------------------------------------------------
+ -------------------------------------------
   0     Domain-0    running    Mailserver 1
   2     fedora      paused