Add OLED bonnet details and pin-out

src/hardware/gpio_pinout.md

@@ -1 +1,16 @@
 # GPIO Pinout
+
+### OLED Bonnet
+
+```
+3v3 Power                       -   1
+BCM 2       (SDA)               -   3
+BCM 3       (SCL)               -   5
+BCM 4       (joystick center)   -   7
+BCM 17      (joystick up)       -   11
+BCM 27      (joystick left)     -   13
+BCM 22      (joystick down)     -   15
+BCM 23      (joystick right)    -   16
+BCM 5       (button A)          -   29
+BCM 6       (button B)          -   31
+```

src/hardware/physical_interface.md

@@ -2,7 +2,7 @@
 
 The PeachCloud physical interface consists of a 5-way joystick, two push-buttons and a 128x64 OLED display.
 
-Development is taking place on the [AdaFruit 128x64 1.3" OLED Bonnet](https://www.adafruit.com/product/3531).
+Development is taking place on the [AdaFruit 128x64 1.3" OLED Bonnet](https://www.adafruit.com/product/3531). This bonnet comes in the pHAT form-factor and requires 3.3V power. It uses 9 GPIO pins and communicates over I2C. The included OLED display utilises the SSD1306 driver.
 
 _Note: the 5-way joystick may be replaced by four or five push-buttons in the release version of the physical interface._
 
@@ -33,5 +33,6 @@ Any button or joystick direction can be pressed to wake the display after select
 │   └── DATA RX
 │   └── DATA TX
 ├── Display Off
+├── Reboot
 └── Shutdown
 ```