add reelboard pins for the epaper display and the reset pin (#429)

* machine/reelboard: added descriptive pin names for the epaper display and the reset pin

src/machine/board_reelboard.go

@@ -15,6 +15,13 @@ const (
 	LED_GREEN        Pin = 12
 	LED_BLUE         Pin = 41
 	LED_YELLOW       Pin = 13
+	EPD_BUSY_PIN     Pin = 14
+	EPD_RESET_PIN    Pin = 15
+	EPD_DC_PIN       Pin = 16
+	EPD_CS_PIN       Pin = 17
+	EPD_SCK_PIN      Pin = 19
+	EPD_MOSI_PIN     Pin = 20
+	POWER_SUPPLY_PIN Pin = 32
 )
 
 // User "a" button on the reel board