README: set Python syntax highlighting

Author: glarrain

README.rst

@@ -57,7 +57,9 @@ Code examples
 Replacements for Py2's built-in functions and types are designed to be imported
 at the top of each Python module together with Python's built-in ``__future__``
 statements. For example, this code behaves identically on Python 2.6/2.7 after
-these imports as it does on Python 3.3+::
+these imports as it does on Python 3.3+:
+
+.. code-block:: python
     
     from __future__ import absolute_import, division, print_function
     from future.builtins import (bytes, str, open, super, range,
@@ -127,7 +129,9 @@ these imports as it does on Python 3.3+::
 
 
 There is also support for renamed standard library modules in the form of import
-hooks. The context-manager form works like this::
+hooks. The context-manager form works like this:
+
+.. code-block:: python
 
     from future import standard_library
 
@@ -164,15 +168,19 @@ mostly unchanged on both Python 2 and Python 3.
 Futurize: 2 to both
 --------------------
 
-For example, running ``futurize -w mymodule.py`` turns this Python 2 code::
+For example, running ``futurize -w mymodule.py`` turns this Python 2 code:
+
+.. code-block:: python
     
     import ConfigParser
 
     class Blah(object):
         pass
     print 'Hello',
 
-into this code which runs on both Py2 and Py3::
+into this code which runs on both Py2 and Py3:
+
+.. code-block:: python
     
     from __future__ import print_function
     from future import standard_library