Brick ref topics 02 (#283)

* Add brick button topics

* Add the rest of the brick api

libs/core/battery.ts

@@ -5,6 +5,7 @@ namespace brick {
      */
     //% blockId=brickBatteryLevel block="battery level"
     //% group="More"
+    //% help=brick/battery-level
     export function batteryLevel(): number {
         const info = sensors.internal.getBatteryInfo();
         return info.current;