Added a line to the documentation to further explain the use of logconfig_dict

Added a line to make the question "how to use `logconfig_dict`" way easier to answer.

docs/source/settings.rst

@@ -321,6 +321,8 @@ older file configuration format.
 
 Format: https://docs.python.org/3/library/logging.config.html#logging.config.dictConfig
 
+For more context you can look at the default configuration dictionary for logging, which can be found at ``gunicorn.glogging.CONFIG_DEFAULTS``.
+
 .. versionadded:: 19.8
 
 .. _syslog-addr: