Use same title as in Installation Assistant which is also more descriptive

wiki/src/doc/advanced_topics.index.mdwn

   - [[!traillink Installing_additional_software|advanced_topics/additional_software]]
   - [[!traillink Protection_against_cold_boot_attacks|advanced_topics/cold_boot_attacks]]
-  - [[!traillink Virtualization|advanced_topics/virtualization]]
+  - [[!traillink Running_Tails_in_a_virtual_machine|advanced_topics/virtualization]]
     - [[!traillink <span_class="application">VirtualBox</span>|advanced_topics/virtualization/virtualbox]]
     - [[!traillink <span_class="application">GNOME_Boxes</span>|advanced_topics/virtualization/boxes]]
     - [[!traillink <span_class="application">virt-manager</span>|advanced_topics/virtualization/virt-manager]]

wiki/src/doc/advanced_topics/virtualization.mdwn

-[[!meta title="Virtualization"]]
+[[!meta title="Running Tails in a virtual machine"]]
 
 [[!toc levels=2]]