Brick ref topics 02 (#283)

* Add brick button topics

* Add the rest of the brick api

docs/reference/brick/button/is-pressed.md

@@ -0,0 +1,53 @@
+# is Pressed
+
+Check if a button is being pressed or not.
+
+```sig
+brick.buttonEnter.isPressed()
+```
+
+## ~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
+if (sensors.touch1.isPressed()) {
+    console.log("Hey, I feel pressed.");
+}
+```
+
+Read about [touch sensors](/reference/sensors/touch-sensor) and using them as touch buttons.
+
+## ~
+
+## Returns
+
+* a [boolean](types/boolean): `true` if the button is pressed, `false` if the button is not pressed
+
+## Example
+
+Set the brick light to green when the `down` is pressed. When the button is not pressed, the brick light is red.
+
+```blocks
+let isRed = false;
+loops.forever(function() {
+    if (brick.buttonLeft.isPressed()) {
+        brick.setLight(BrickLight.Green);
+        isRed = false;
+    } else {
+        if (!isRed) {
+            brick.setLight(BrickLight.Red);
+            isRed = true;
+        }
+    }
+})
+```
+
+## See also
+
+[was pressed](/reference/brick/button/was-pressed),
+[on event](/reference/brick/button/on-event)
+
+[Touch sensors](/reference/sensors/touch-sensor)