message: Update README.md
  CubeMX2Makefile requires python2 rather than 3
diff: @@ -65,7 +65,7 @@ We also use a tool to generate the Makefile. The steps to do this are as follows
  ### Generate makefile
  There is an excellent project called CubeMX2Makefile, originally from baoshi. This project is included as a submodule.
  * Initialise and clone the submodules: `git submodule init; git submodule update`
  -* Generate makefile: `CubeMX2Makefile/CubeMX2Makefile.py .`
  +* Generate makefile: `python2 CubeMX2Makefile/CubeMX2Makefile.py .`
  ## Setting up Eclipse development environment
  