Clarify MotorHat disposal/ownership semantics in README

src/devices/MotorHat/README.md

@@ -41,6 +41,55 @@ using (var motorHat = new MotorHat())
 
 Check the [ServoMotor documentation](../ServoMotor/README.md) for examples on how to use the ServoMotor class
 
+## Resource management (disposing)
+
+The `MotorHat` owns all the resources it creates. When you call `CreateDCMotor`, `CreateServoMotor` or `CreatePwmChannel`, the returned object uses PWM channels that belong to the `MotorHat`'s underlying PCA9685 controller.
+
+Because of this ownership model:
+
+- **Disposing the `MotorHat` is enough.** `MotorHat.Dispose()` stops every channel it handed out and then disposes the underlying PCA9685 (and its I2C device). You do not need to dispose the motors, servos or PWM channels separately.
+- **Disposing a motor as well is safe.** Disposing a `DCMotor` created by `CreateDCMotor` only stops its PWM channels; it does not dispose them. Combined with the point above, disposing both the motor and the `MotorHat` will not throw or leave the board in a random state.
+- **Order does not matter.** You can dispose the motors before or after the `MotorHat`; the result is the same.
+
+The recommended pattern is to keep the objects you need alive for as long as the `MotorHat` and let a single `using` (or `Dispose`) on the `MotorHat` clean everything up:
+
+```csharp
+using (var motorHat = new MotorHat())
+{
+    var motor = motorHat.CreateDCMotor(1);
+
+    motor.Speed = 1;
+
+    // ... use the motor ...
+
+    // No need to dispose 'motor' explicitly; disposing 'motorHat' releases it.
+}
+```
+
+If you wrap the `MotorHat` in your own class, forward disposal to the `MotorHat`. Disposing the individual motors as well is harmless but not required:
+
+```csharp
+public class PumpController : IDisposable
+{
+    private MotorHat _motorHat = new MotorHat();
+    private List<DCMotor> _motors = new List<DCMotor>();
+
+    public void Initialize()
+    {
+        _motors.Add(_motorHat.CreateDCMotor(1));
+    }
+
+    // ... use the motors ...
+
+    public void Dispose()
+    {
+        // Disposing the MotorHat stops and releases every motor/channel it created.
+        // Order is not important and disposing the motors as well would be safe.
+        _motorHat.Dispose();
+    }
+}
+```
+
 ## Support
 
 - Up to 4 DC Motors