remove option --debug and update documents

docs/source/settings.rst

@@ -244,17 +244,6 @@ on the allowed size of an HTTP request header field.
 Debugging
 ---------
 
-debug
-~~~~~
-
-* ``--debug``
-* ``False``
-
-Turn on debugging in the server.
-
-**DEPRECATED**: This no functionality was removed after v18.0.
-This option is now a no-op.
-
 reload
 ~~~~~~
 
@@ -959,3 +948,11 @@ statsd_host
 
 host:port of the statsd server to log to
 
+statsd_prefix
+~~~~~~~~~~~~~
+
+* ``--statsd-prefix STATSD_PREFIX``
+* ````
+
+prefix to use when emitting statsd metrics (a trailing . is added, if not provided)
+

examples/example_config.py

@@ -75,14 +75,6 @@ worker_connections = 1000
 timeout = 30
 keepalive = 2
 
-#
-# Debugging
-#
-#   debug - Turn on debugging in the server. This limits the number of
-#       worker processes to 1 and changes some error handling that's
-#       sent to clients.
-#
-#       True or False
 #
 #   spew - Install a trace function that spews every line of Python
 #       that is executed when running the server. This is the
@@ -91,7 +83,6 @@ keepalive = 2
 #       True or False
 #
 
-debug = False
 spew = False
 
 #

gunicorn/config.py

@@ -755,21 +755,6 @@ class LimitRequestFieldSize(Setting):
         """
 
 
-class Debug(Setting):
-    name = "debug"
-    section = "Debugging"
-    cli = ["--debug"]
-    validator = validate_bool
-    action = "store_true"
-    default = False
-    desc = """\
-        Turn on debugging in the server.
-
-        **DEPRECATED**: This no functionality was removed after v18.0.
-        This option is now a no-op.
-        """
-
-
 class Reload(Setting):
     name = "reload"
     section = 'Debugging'