Doc: add missing note about permissions needed to change log_lock_waits.

log_lock_waits is PGC_SUSET, but config.sgml lacked the standard
boilerplate sentence noting that.

Report: https://postgr.es/m/20170719100838.19352.16320@wrigleys.postgresql.org

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 036228df436a60137267072a41cf48017a691cc4..cbb207d59c5e8a9615ad7a6b27f649824d54ba8b 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4716,6 +4716,7 @@ FROM pg_stat_activity;
         longer than <xref linkend="guc-deadlock-timeout"> to acquire a
         lock.  This is useful in determining if lock waits are causing
         poor performance.  The default is <literal>off</>.
+        Only superusers can change this setting.
        </para>
       </listitem>
      </varlistentry>