Hi and welcome.

You can use another small piece of wire if you want to bridge the two terminals, but you'd normally just strip enough insulation off the wire leading to the tone pot so that you can push it through one tab hole on the switch and run it through the other tab hole, then solder the wire to both switch tabs.

I haven't looked at that wiring diagram before, but there is something definitely not normal about the way the tone pots are shown wired. I don't know how much of this is pre-wired, but the diagram needs some correcting. I'll see if I can get someone to have a look at it.