Add reference to slapd.conf(5) and recommendation to avoid cleartext passwords.

servers/slapd/slapd.conf

+#
+# See slapd.conf(5) for details on configuration options.
+#
 include		%SYSCONFDIR%/slapd.at.conf
 include		%SYSCONFDIR%/slapd.oc.conf
 schemacheck	off
@@ -14,3 +17,5 @@ directory	/usr/tmp
 rootdn		"cn=root, dc=your-domain, dc=com"
 #rootdn		"cn=root, o=Your Organization Name, c=US"
 rootpw		secret
+# cleartext passwords, especially for the rootdn, should
+# be avoid.  See slapd.conf(5) for details.