Fix Typo

Micro-Python-on-Mac-OSX.md

@@ -81,7 +81,7 @@ I installed python34 using ports (as in the first part of this wiki page) and my
 I executed the following commands to install the patched version:
 ```
 cd /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/serial/tools
-sudo cp list_ports_os.py list_ports_osx_original.py
+sudo cp list_ports_osx.py list_ports_osx_original.py
 sudo curl -O http://sourceforge.net/p/pyserial/patches/_discuss/thread/603bd426/55a8/attachment/list_ports_osx.py
 ```
 Now I was able to execute the list_ports.comports() example posted above under python3 and it produced the correct output.