Small fixes in documentation

Changelog.rst

@@ -669,7 +669,7 @@
 
 - Fixed string handling when using python-future module
 
-    Contributed by **John Koehl"
+    Contributed by **John Koehl**
 
 - Replaced "async" with "asynchronous" in preparation for Python 3.7
 

docs/userguide/producers.rst

@@ -27,6 +27,7 @@ it takes a channel or a connection as an argument:
 Having a producer instance you can publish messages:
 
 .. code-block:: pycon
+
     >>> from kombu import Exchange
 
     >>> exchange = Exchange('name', type='direct')

requirements/docs.txt

@@ -1,6 +1,7 @@
 git+https://github.com/celery/sphinx_celery.git
 -r extras/mongodb.txt
 -r extras/sqlalchemy.txt
+-r extras/azureservicebus.txt
 # we cannot use directly extras/sqs.txt
 # since readthedocs cannot install pycurl
 boto3>=1.4.4