Nrf52832 changing advertising led to gpio and external led


I'm working with the Nrf52832 Dev Kit and the ble_uart_example. After flashing with the hex file and powering the Dev Kit, the on-board-LED starts to blink. Now I want to use an external LED connected to a GPIO to show if the Board is advertising(led blinking) or connected(led on). What changes in the software must be made that the GPIO with an external LED can be used as an indicator for advertising. I tried to change the pins in bsp_config.h but it wasn't successful.

Best regards!