check_ntp_peer: Fix --help output for -W and -C

Mention that the check_ntp_peer plugin checks the stratum of the
synchronization peer, not the stratum of the monitored server itself.

Thanks to Marc Haber for bringing this up on the "nagios-users" mailing
list (Message-ID: <20120722142840.GA6931@torres.zugschlus.de>).

plugins/check_ntp_peer.c

@@ -668,9 +668,9 @@ void print_help(void){
 	printf (" %s\n", "-c, --critical=THRESHOLD");
 	printf ("    %s\n", _("Offset to result in critical status (seconds)"));
 	printf (" %s\n", "-W, --swarn=THRESHOLD");
-	printf ("    %s\n", _("Warning threshold for stratum"));
+	printf ("    %s\n", _("Warning threshold for stratum of server's synchronization peer"));
 	printf (" %s\n", "-C, --scrit=THRESHOLD");
-	printf ("    %s\n", _("Critical threshold for stratum"));
+	printf ("    %s\n", _("Critical threshold for stratum of server's synchronization peer"));
 	printf (" %s\n", "-j, --jwarn=THRESHOLD");
 	printf ("    %s\n", _("Warning threshold for jitter"));
 	printf (" %s\n", "-k, --jcrit=THRESHOLD");