I did the change and I'm very happy with the new reboot button and the good instructions.

But I think that a noob that never has read xml-files could make dangerous things to systemui.xml.
E.g. if he uncomments one part of the tag and forgets the other part.
This would make the whole xml-file unreadeable.

The instructions are very precise.
But it would be good to show to a noob exactly how the text looks before and how it looks after the changings.