📝 Add STM32F4 example, Ruby (MarlinFirmware#24399)

Author: shleeable

README.md

@@ -48,7 +48,7 @@ Marlin 2.0 introduces a layer of abstraction so that all the existing high-level
   [LPC1768](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/lpc1700-cortex-m3/512-kb-flash-64-kb-sram-ethernet-usb-lqfp100-package:LPC1768FBD100)|ARM® Cortex-M3|MKS SBASE, Re-ARM, Selena Compact
   [LPC1769](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/lpc1700-cortex-m3/512-kb-flash-64-kb-sram-ethernet-usb-lqfp100-package:LPC1769FBD100)|ARM® Cortex-M3|Smoothieboard, Azteeg X5 mini, TH3D EZBoard
   [STM32F103](https://www.st.com/en/microcontrollers-microprocessors/stm32f103.html)|ARM® Cortex-M3|Malyan M200, GTM32 Pro, MKS Robin, BTT SKR Mini
-  [STM32F401](https://www.st.com/en/microcontrollers-microprocessors/stm32f401.html)|ARM® Cortex-M4|ARMED, Rumba32, SKR Pro, Lerdge, FYSETC S6
+  [STM32F401](https://www.st.com/en/microcontrollers-microprocessors/stm32f401.html)|ARM® Cortex-M4|ARMED, Rumba32, SKR Pro, Lerdge, FYSETC S6, Artillery Ruby
   [STM32F7x6](https://www.st.com/en/microcontrollers-microprocessors/stm32f7x6.html)|ARM® Cortex-M7|The Borg, RemRam V1
   [SAMD51P20A](https://www.adafruit.com/product/4064)|ARM® Cortex-M4|Adafruit Grand Central M4
   [Teensy 3.5](https://www.pjrc.com/store/teensy35.html)|ARM® Cortex-M4|