doc: Remove formal language from code directive in README.rst

This change is intended to work around a pypi limitation re
not supporting formal language directives, causing pypi to
give up and render the document as plaintext vs HTML.

Kudos to rafaelmartins on IRC for pointing me in the right
direction on this!

README.rst

@@ -46,20 +46,20 @@ Features
 Install
 ~~~~~~~
 
-.. code:: bash
+.. code::
 
     $ pip install cython falcon
 
 Test
 ~~~~
 
-.. code:: bash
+.. code::
 
     $ pip install nose && nosetests
 
 To test across all supported Python versions:
 
-.. code:: bash
+.. code::
 
     $ pip install tox && tox
 
@@ -75,7 +75,7 @@ them right away, consider sending a pull request. ;)
 
 Here is a simple example showing how to create a Falcon-based API.
 
-.. code:: python
+.. code::
 
     class ThingsResource:
         def on_get(self, req, resp):
@@ -95,7 +95,7 @@ Here is a simple example showing how to create a Falcon-based API.
 Here is a more involved example, demonstrating getting headers and query
 parameters, handling errors, and reading/writing message bodies.
 
-.. code:: python
+.. code::
 
 
     import json