Turn off the Adafruit Capacitive Touch PiTFT Plus Display (#2423) on power-off

Using a device tree overlay it is easy to turn off the Adafruit display backlight once the Pi goes into power-off state.Simply add the following line to the end of /boot/config.txtdtoverlay=gpio-poweroff,gpiopin=18,active_low="y"This will drive this particular pin #18 (which is responsible for the backlight on the Adafruit PiTFT display) low on shutdown, and will keep it [...]