feat: add Flywheel example documentation with Kotlin and Java implementations

Author: zachwaffle4

src/control/examples/flywheels.md

@@ -0,0 +1,106 @@
+# Flywheel Example
+
+Flywheels are a commonly used mechanism in FTC for launching game elements, 
+and most often controlled with a velocity PID feedback controller.
+
+With NextControl, that would be implemented like this (using hypothetical constants):
+
+::: tabs key:code
+
+== Kotlin
+
+```kotlin
+controlSystem {
+    velPid(0.001, 0.0, 0.0)
+}
+```
+
+== Java
+
+```java
+ControlSystem.builder()
+             .velPid(0.001, 0.0, 0.0)
+             .build();
+```
+
+:::
+
+## What can I do with this?
+
+If you're using a command-based framework, like NextFTC, 
+you can create commands using your control system.
+
+If not, we can create OpModes that use our controllers directly. 
+For example, let's say we wanted to change the target velocity of our flywheel using a button press.
+We can easily do that by simply changing the `goal` of our `ControlSystem`:
+
+::: tabs key:code 
+
+== Kotlin
+
+```kotlin
+class FlywheelExample() : OpMode() {
+    val flywheelMotor by lazy { hardwareMap.get(DcMotorEx.class, "flywheel") }
+    val controller = controlSystem {
+        velPid(0.001, 0.0, 0.0)
+    }
+
+    override fun init() {
+        controller.goal = KineticState(0.0)
+    }
+
+    override fun loop() {
+        if (gamepad1.aWasPressed()) {
+            controller.goal = KineticState(0.0, 2000.0)
+        } else if (gamepad1.bWasPressed()) {
+            controller.goal = KineticState(0.0, 0.0)
+        } else if (gamepad1.xWasPressed()) {
+            controller.goal = KineticState(0.0, 1000.0)
+        }
+
+        flywheelMotor.power = controller.calculate(
+            flywheelMotor.currentPosition,
+            flywheelMotor.velocity
+        )
+    }
+}
+```
+
+== Java
+
+```java 
+public class FlywheelExample extends OpMode {
+    private DcMotorEx flywheelMotor;
+    private ControlSystem controller;
+
+    @Override
+    public void init() {
+        flywheelMotor = hardwareMap.get(DcMotorEx.class, "flywheel");
+        
+        controller = ControlSystem.builder()
+             .velPid(0.001, 0.0, 0.0)
+             .build();
+        
+        controller.goal = new KineticState(0.0);
+    }
+
+    @Override
+    public void loop() {
+        if (gamepad1.aWasPressed()) {
+            controller.goal = new KineticState(0.0, 2000.0);
+        } else if (gamepad1.bWasPressed()) {
+            controller.goal = new KineticState(0.0, 0.0);
+        } else if (gamepad1.xWasPressed()) {
+            controller.goal = new KineticState(0.0, 1000.0);
+        }
+
+        flywheelMotor.setPower(controller.calculate(
+            flywheelMotor.getCurrentPosition(),
+            flywheelMotor.getVelocity()
+        ));
+    }
+}
+```
+
+:::
+