Add docs for the servo hat on the arduino

Author: RealOrangeOne

content/api/arduino.md

@@ -132,3 +132,37 @@ distance_metres = u.distance()
 If the ultrasound signal never returns, the sensor will timeout and
 return `None`.
 {{% /notice %}}
+
+## Servos
+
+{{% notice warning %}}
+Servos are only available on the [physical robot](/robots/physical/).
+{{% /notice %}}
+
+You can control attached servo motors from the servo assembly. By default, servos will be unpowered when your robot starts, and can freely rotate when turned by hand. Upon setting a value, they will hold the corresponding position. They will become unpowered again when you turn off your robot, unplug your USB stick, or set their position to the special value `None`.
+
+## Querying servos
+
+The servo assembly can interface with up to sixteen servos connected to it.
+
+```python
+servo_one = r.arduino.servos[1]
+```
+
+{{% notice tip %}}
+Servo can be connected to any port, you don't have to start at 0!
+{{% /notice %}}
+
+## Controlling servos
+
+Servos can be controlled using the `position` parameter. This should be set to a value between -1 and 1.
+
+```python
+servo_one.position = 0.65
+print(servo_one.position)
+>>> 0.65
+```
+
+{{% notice tip %}}
+When `position` is set to `None`, the servo loses power and can freely rotate. This is the same state they're in at start-up.
+{{% /notice %}}