L2SS-445: Added documentation for adding log sources

docs/source/developer.rst

@@ -89,13 +89,10 @@ The ``common.lofar_logging`` module provides an easy way to log to the ELK stack
 Log from Docker
 `````````````````
 
-Not all Docker containers run our Python programs, and can forward the logs themselves. For those, we use the ``syslog`` log driver in Docker. Extend the ``docker compose`` files with::
-
-  logging:
-    driver: syslog
-    options:
-      syslog-address: udp://${HOSTNAME}:1514
-      syslog-format: rfc3164
-      tag: "{{.Name}}"
+Not all Docker containers run our Python programs, and can forward the logs themselves. For those, we use the ``syslog`` log driver in Docker. Extend the ``docker compose`` files with:
+
+.. literalinclude:: ../../docker-compose/rest.yml
+   :start-at: logging:
+   :end-before: restart:
 
 Logs forwarded in this way are provided with the container name, their timestamp, and a log level guessed by Docker. It is thus wise to parse the message content further in Logstash (see above).