Improve index page for topic guides.

Author: aaugustin

docs/topics/authentication.rst

@@ -313,8 +313,8 @@ To authenticate a websockets client with HTTP Basic Authentication
     async with connect(f"wss://{username}:{password}@.../") as websocket:
         ...
 
-(You must :func:`~urllib.parse.quote` ``username`` and ``password`` if they
-contain unsafe characters.)
+You must :func:`~urllib.parse.quote` ``username`` and ``password`` if they
+contain unsafe characters.
 
 To authenticate a websockets client with HTTP Bearer Authentication
 (:rfc:`6750`), add a suitable ``Authorization`` header:

docs/topics/index.rst

@@ -1,18 +1,26 @@
 Topic guides
 ============
 
-Get a deeper understanding of how websockets is built and why.
+These documents discuss how websockets is designed and how to make the best of
+its features when building applications.
 
 .. toctree::
-   :titlesonly:
+   :maxdepth: 2
 
    authentication
    broadcast
+   logging
+   proxies
+   routing
+
+These guides describe how to optimize the configuration of websockets
+applications for performance and reliability.
+
+.. toctree::
+   :maxdepth: 2
+
    compression
    keepalive
-   logging
    memory
    security
    performance
-   proxies
-   routing