DOC: management: -q is quiet all the time

The documentation about -q seems wrong, it does not output messages
after the startup, it disables all messages. It was always quiet with
the stdio_quiet() function.

Must be backported in all stable versions.

(cherry picked from commit 705a72fd1937fb1e9247c19c81a1ce4b98a57b36)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/doc/management.txt b/doc/management.txt
index e22e301..7e2e5de 100644
--- a/doc/management.txt
+++ b/doc/management.txt
@@ -420,9 +420,8 @@
     before entering the chroot jail, and after doing the chdir() implied by
     "-C". Each pid appears on its own line.
 
-  -q : set "quiet" mode. This disables some messages during the configuration
-    parsing and during startup. It can be used in combination with "-c" to
-    just check if a configuration file is valid or not.
+  -q : set "quiet" mode. This disables the output messages. It can be used in
+    combination with "-c" to just check if a configuration file is valid or not.
 
   -S <bind>[,bind_options...]: in master-worker mode, bind a master CLI, which
     allows the access to every processes, running or leaving ones.