Consolidate 'coding' activities into single pages (#354)

docs/coding/cruise-control.md

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+# Cruise Control
+
+Learn how to set and adjust motor speeds.
+
+## Activity 1
+
+Increase motor speed when touch sensor `1` is pressed.
+
+```blocks
+let speed = 0;
+sensors.touch1.onEvent(ButtonEvent.Pressed, function () {
+    if (speed < 100)
+        speed = speed + 10;
+    motors.largeBC.run(speed);
+}) 
+```
+
+## Activity 2
+
+Add a "reduce" motor speed action when touch sensor `2` is pressed.
+
+```blocks
+let speed = 0;
+sensors.touch1.onEvent(ButtonEvent.Pressed, function () {
+    if (speed < 100)
+        speed = speed + 10;
+    motors.largeBC.run(speed);
+}) 
+sensors.touch2.onEvent(ButtonEvent.Pressed, function () {
+    if (speed > -100)
+        speed = speed - 10;
+    motors.largeBC.run(speed);
+}) 
+```
+
+## Activity 3
+
+Refactor your code by moving the speed increase and speed decrease code into ``||functions:accelerate||`` and ``||functions:decelerate||`` functions. Run the motors at the new speed in an ``||functions:update||`` function.
+
+```blocks
+let speed = 0
+function decelerate() {
+    if (speed > -100) {
+        speed = speed - 10
+    }
+}
+function accelerate() {
+    if (speed < 100) {
+        speed = speed + 10
+    }
+}
+function update() {
+    brick.clearScreen()
+    brick.showString("speed: " + speed, 1)
+    motors.largeBC.run(speed)
+}
+sensors.touch2.onEvent(ButtonEvent.Pressed, function () {
+    accelerate()
+    update()
+})
+sensors.touch1.onEvent(ButtonEvent.Pressed, function () {
+    decelerate()
+    update()
+})
+```