Brick ref topics 02 (#283)

* Add brick button topics

* Add the rest of the brick api

docs/reference/brick/button/on-event.md

@@ -0,0 +1,57 @@
+# on Event
+
+Run some code when a button is clicked, pressed down, or released.
+
+```sig
+brick.buttonEnter.onEvent(ButtonEvent.Click, function () {
+
+});
+```
+
+## ~hint
+
+**Touch sensors**
+
+Your @boardname@ has touch sensors that work like buttons. Instead of saying `enter` or `left` as the source button, use a touch sensor block with a sensor name like `touch 1`.
+
+```block
+sensors.touch1.onEvent(TouchSensorEvent.Pressed, function () {
+    brick.setLight(BrickLight.Orange);
+});
+```
+
+Read about [touch sensors](/reference/sensors/touch-sensor) and using them as touch buttons.
+
+## ~
+
+## Parameters
+
+* **ev**: the button action to run some code for. The button actions (events) are:
+> * ``click``: button was clicked (pressed and released)
+> * ``up``: button is released from just being pressed
+> * ``down``: button is just pressed down
+* **body**: the code you want to run when something happens with a button
+
+## Example
+
+Check for event on the ENTER button. Put a message on the screen when the button is pressed, clicked, or released.
+
+```blocks
+brick.showString("ENTER is: UP", 1);
+brick.buttonEnter.onEvent(ButtonEvent.Up, function () {
+    brick.showString("ENTER is: UP      ", 1);
+});
+brick.buttonEnter.onEvent(ButtonEvent.Down, function () {
+    brick.showString("ENTER is: DOWN    ", 1);
+});
+brick.buttonEnter.onEvent(ButtonEvent.Click, function () {
+    brick.showString("ENTER was: CLICKED", 1);
+});
+```
+
+### See also
+
+[is pressed](/reference/brick/button/is-pressed),
+[was pressed](/reference/brick/button/was-pressed),
+
+[Touch sensor](/reference/sensors/touch-sensor)