add installation instructions for MAC to readme

[raphaelquast]

• right-click the Live-icon in your program-folder and chose "show-contents"

• navigate to:
  /Contents/App-Resources/MIDI Remote Scripts/

associated discussion: Reddit - question

... wait for confirmation from a MAC user before putting it in the README

MacOS compatibility is not yet working... need to fix #58 before putting this into README

[raphaelquast]

#80 has to be fixed first