Sync CreateVirtualMachineLinuxTutorial.md

Sync step 11 in CreateVirtualMachineLinuxTutorial.md (using /etc/fstab
and UUIDs) with identical information in
howto-attach-disk-windows-linux.md committed earlier.
Merge pull request #1685 from szarkos/FSTAB_UUID

Sync CreateVirtualMachineLinuxTutorial.md