[How to do instruction] Use hardware momentary switches to control moOde

[remy1961]

On the hardware side, you set your hardware button to connect the ground pin of your RPi with a GPIO pin of your choice.

So you should be able to strip the ends of a couple of dupont cables, connect the plug ends to ground and selected pin then briefly touch the bare ends together. 
Happy to test it here...

Hi. As explained here it actually depends on the "default pull status" of the GPIO: if the default pull status is low, you connect the gpio to the 3.3 volts pin (never connect with the 5 volts pin). If the default status is high, you connect to the ground. 

Remy