format helloworld

Author: mysterywolf

zh/beginner/helloworld-led.md

@@ -40,4 +40,7 @@ void loop(void)
 
 由于每个 BSP 的板子设计、以及芯片型号等，引脚分布是有区别的，因此需要到指定 BSP 的 `applications/arduino` 文件夹下的README.md文件查看详细信息。例如：
 
-[STM32F401 Nucleo板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f401-st-nucleo/applications/arduino_pinout) | [STM32F411 Nucleo板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f411-st-nucleo/applications/arduino_pinout) | [STM32L475潘多拉板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32l475-atk-pandora/applications/arduino_pinout)
+- [STM32F401 Nucleo板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f401-st-nucleo/applications/arduino_pinout)
+- [STM32F411 Nucleo板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f411-st-nucleo/applications/arduino_pinout)
+- [STM32F407星火一号的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f407-rt-spark/applications/arduino_pinout)
+- [STM32L475潘多拉板的Arduino引脚布局的详细说明](https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32l475-atk-pandora/applications/arduino_pinout)