DOC: fix misleading information about SIGQUIT

SIGQUIT dumps the pools state to stderr, not to the logs. Thanks to
Jim Freeman for reporting this.
diff --git a/doc/haproxy.1 b/doc/haproxy.1
index c9f159a..ee29c03 100644
--- a/doc/haproxy.1
+++ b/doc/haproxy.1
@@ -181,7 +181,7 @@
 Dumps the status of all proxies and servers into the logs. Mostly used for trouble-shooting purposes.
 .TP
 \- \fBSIGQUIT\fP
-Dumps information about memory pools into the logs. Mostly used for debugging purposes.
+Dumps information about memory pools on stderr. Mostly used for debugging purposes.
 .TP
 \- \fBSIGPIPE\fP
 This signal is intercepted and ignored on systems without \fBMSG_NOSIGNAL\fP.