Fix typos in porting.rst (#939)

Author: rshah713

developer-workflow/porting.rst

@@ -12,12 +12,12 @@ Next, learn how to compile and run the Python interpreter on a platform to
 which it has already been ported; preferably Unix, but Windows will
 do, too. The build process for Python, in particular the ``Makefile`` in the
 source distribution, will give you a hint on which files to compile
-for Python.  Not all source files are relevant: some are platform
-specific, others are only used in emergencies (e.g. ``getopt.c``).
+for Python.  Not all source files are relevant: some are platform-specific,
+and others are only used in emergencies (e.g. ``getopt.c``).
 
-It is not recommended to start porting Python without at least medium-level
+It is not recommended to start porting Python without at least a medium-level
 understanding of your target platform; i.e. how it is generally used, how to
-write platform specific apps, etc. Also, some Python knowledge is required, or
+write platform-specific apps, etc. Also, some Python knowledge is required, or
 you will be unable to verify that your port is working correctly.
 
 You will need a ``pyconfig.h`` file tailored for your platform.  You can