Fixed Sphinx build warnings.

Closes #1463.

docs/one-to-two.rst

@@ -162,10 +162,10 @@ storing it on ``self`` inside a consumer.
 HTTP sessions and Django auth
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-All :doc:`authentication </topics/authentication>` and
-:doc:`sessions </topics/session>` are now done with middleware. You can remove
-any decorators that handled them, like ``http_session``, ``channel_session_user``
-and so on (in fact, there are no decorators in Channels 2 - it's all middleware).
+All :doc:`authentication <topics/authentication>` and :doc:`sessions
+<topics/sessions>` are now done with middleware. You can remove any decorators
+that handled them, like ``http_session``, ``channel_session_user`` and so on
+(in fact, there are no decorators in Channels 2 - it's all middleware).
 
 To get auth now, wrap your URLRouter in an ``AuthMiddlewareStack``:
 

docs/topics/channel_layers.rst

@@ -38,7 +38,7 @@ You can get the default channel layer from a project with
 is automatically provided for you on the consumer as ``self.channel_layer``.
 
 Redis Channel Layer
-**********************
+*******************
 
 `channels_redis`_ is the only official Django-maintained channel layer
 supported for production use. The layer uses Redis as its backing store,
@@ -62,7 +62,7 @@ In this example, Redis is running on localhost (127.0.0.1) port 6379:
     }
 
 In-Memory Channel Layer
-**********************
+***********************
 
 .. warning::