[doc]: Update logging cookbook to mention domain socket configuration in a recipe.

Author: vsajip

Doc/howto/logging-cookbook.rst

@@ -825,16 +825,29 @@ To test these files, do the following in a POSIX environment:
    which will lead to records being written to the log.
 
 #. Inspect the log files in the :file:`run` subdirectory. You should see the
-   most recent log lines in files matching the pattern :file:`app.log*`. They won't be in
-   any particular order, since they have been handled concurrently by different
-   worker processes in a non-deterministic way.
+   most recent log lines in files matching the pattern :file:`app.log*`. They
+   won't be in any particular order, since they have been handled concurrently
+   by different worker processes in a non-deterministic way.
 
 #. You can shut down the listener and the web application by running
    ``venv/bin/supervisorctl -c supervisor.conf shutdown``.
 
 You may need to tweak the configuration files in the unlikely event that the
 configured ports clash with something else in your test environment.
 
+The default configuration uses a TCP socket on port 9020. You can use a Unix
+Domain socket instead of a TCP socket by doing the following:
+
+#. In `listener.json`, add a `socket` key with the path to the domain socket
+   you want to use. If this key is present, the listener listens on the
+   corresponding domain socket and not on a TCP socket (the `port` key is
+   ignored).
+
+#. In `webapp.json`, change the socket handler configuration dictionary so that
+   the `host` value is the path to the domain socket, and set the `port` value
+   to `null`.
+
+
 .. currentmodule:: logging
 
 .. _context-info: