work on pro LED, add rainbow test

watch-library/shared/watch/watch_led.h

@@ -63,6 +63,16 @@ void watch_disable_leds(void);
   */
 void watch_set_led_color(uint8_t red, uint8_t green);
 
+/** @brief On boards with an RGB LED, sets the LED to a custom color by modulating each output's duty cycle.
+  * @param red The red value from 0-255.
+  * @param green The green value from 0-255.
+  * @param blue The blue value from 0-255.
+  * @note If you are displaying a custom color, you will need to prevent your app from going to sleep
+  *       while the LED is on; otherwise, the color will not display correctly. You can do this by
+  *       returning false in your app_loop method.
+  */
+void watch_set_led_color_rgb(uint8_t red, uint8_t green, uint8_t blue);
+
 /** @brief Sets the red LED to full brightness, and turns the green LED off.
   * @details Of the two LED's in the RG bi-color LED, the red LED is the less power-efficient one (~4.5 mA).
   */