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

docs/coding/ignition.md

@@ -0,0 +1,48 @@
+# Ignition
+
+Explore sensor events and sensor status.
+
+## Activity 1
+
+Wait for a touch sensor press or ultrasonic object detection. Show an expression on the screen when they happen.
+
+```blocks
+sensors.touch1.onEvent(ButtonEvent.Pressed, function () {
+    brick.showImage(images.eyesDizzy)
+})
+sensors.ultrasonic4.onEvent(UltrasonicSensorEvent.ObjectDetected, function () {
+    brick.showImage(images.eyesTiredMiddle)
+})
+brick.showImage(images.eyesSleeping)
+```
+
+## Activity 2
+
+Play some motor sounds if touch sensor `1` is pressed at the same moment when and object comes close.
+
+```blocks
+while (true) {
+    if (sensors.touch1.wasPressed() &&
+        sensors.ultrasonic4.distance() < 10) {
+        music.playSoundEffectUntilDone(sounds.mechanicalMotorStart)
+        music.playSoundEffectUntilDone(sounds.mechanicalMotorIdle);
+    }
+    pause(1);
+}
+```
+
+## Activity 3
+
+Play some motor sounds if touch sensor `1` is pressed when both the `enter` button is pressed on the brick and an object comes close.
+
+```blocks
+while (true) {
+    if (sensors.ultrasonic4.distance() < 10 &&
+        sensors.touch1.wasPressed() &&
+        brick.buttonEnter.wasPressed()) {
+        music.playSoundEffectUntilDone(sounds.mechanicalMotorStart)
+        music.playSoundEffectUntilDone(sounds.mechanicalMotorIdle);
+    }
+    pause(1);
+}
+```