man/systemd-detect-virt: fix row spanning for VM header

This fixes

  commit 9b0688f491
  Author: Yu Watanabe <watanabe.yu+github@gmail.com>
  Date:   Tue Jan 9 10:52:49 2024 +0900

    virt: add Google Compute Engine support

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

man/systemd-detect-virt.xml

@@ -62,7 +62,7 @@
         </thead>
         <tbody>
           <row>
-            <entry valign="top" morerows="16">VM</entry>
+            <entry valign="top" morerows="17">VM</entry>
             <entry><varname>qemu</varname></entry>
             <entry>QEMU software virtualization, without KVM</entry>
           </row>