Fix typo and add config.yaml example for ExtraPins

bin/config-dist.yaml

@@ -105,6 +105,8 @@ Lora:
 
 GPS:
 #  SerialPath: /dev/ttyS0
+#  ExtraPins:
+#    - 22
 
 ### Specify I2C device, or leave blank for none
 

src/platform/portduino/PortduinoGlue.cpp

@@ -488,7 +488,7 @@ void portduinoSetup()
     }
 
     for (auto i : portduino_config.extra_pins) {
-        if (i.enabled && i.gpiochip > max_GPIO)
+        if (i.enabled && i.pin > max_GPIO)
             max_GPIO = i.pin;
     }