Update README.md

Add link to CANOpenSTM32

Author: CANopenNode

README.md

@@ -47,6 +47,7 @@ Related projects
  - [CANopenNode.github.io](https://github.com/CANopenNode/CANopenNode.github.io): Html documentation, compiled by doxygen, for CANopenDemo, CANopenNode and other devices, available also online: https://canopennode.github.io
  - [CANopenEditor](https://github.com/CANopenNode/CANopenEditor): Object Dictionary editor, external GUI tool for editing CANopen Object Dictionary for custom device. It generates C source code, electronic data sheet and documentation for the device. It is a fork from [libedssharp](https://github.com/robincornelius/libedssharp).
  - [CANopenLinux](https://github.com/CANopenNode/CANopenLinux): CANopenNode on Linux devices. It can be a basic CANopen device or more advanced with commander functionalities.
+ - [CANopenSTM32](https://github.com/CANopenNode/CanOpenSTM32): CANopenNode on STM32 microcontrollers.
  - [CANopenPIC](https://github.com/CANopenNode/CANopenPIC): CANopenNode on PIC microcontrollers from Microchip. Works with 16-bit and 32 bit devices. Includes example for Arduino style [Max32](https://reference.digilentinc.com/reference/microprocessor/max32/start) board.
  - [doc/deviceSupport.md](doc/deviceSupport.md): List of other implementations of CANopenNode on different devices.