- use nmea(4) for general sensor example rather than udcf(4)

which only works in w.europe
- use a more realistic value for udcf correction example
- use a GPS-only receiver for "refid GPS" example
suggested/ok mbalmer

src/usr.sbin/ntpd/ntpd.conf.5

@@ -1,4 +1,4 @@
-.\" $OpenBSD: ntpd.conf.5,v 1.20 2008/06/09 16:37:35 ckuethe Exp $
+.\" $OpenBSD: ntpd.conf.5,v 1.21 2008/10/10 12:17:09 sthen Exp $
 .\"
 .\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 .\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: June 9 2008 $
+.Dd $Mdocdate: October 10 2008 $
 .Dt NTPD.CONF 5
 .Os
 .Sh NAME
@@ -92,16 +92,16 @@ does not use any timedelta sensor by default.
 For example:
 .Bd -literal -offset indent
 sensor *
-sensor udcf0
+sensor nmea0
 .Ed
 .Pp
 An optional correction in microseconds can be given to compensate
 for the sensor's offset.
 The maximum correction is 127 seconds.
-For example, if a DCF77 receiver is lagging 15ms behind
+For example, if a DCF77 receiver is lagging 70ms behind
 actual time:
 .Bd -literal -offset indent
-sensor udcf0 correction 15000
+sensor udcf0 correction 70000
 .Ed
 .Pp
 An optional reference ID string - up to 4 ASCII characters - can be
@@ -113,7 +113,7 @@ If an ID string is not given,
 will use a generic reference ID.
 For example:
 .Bd -literal -offset indent
-sensor msts0 refid GPS
+sensor nmea0 refid GPS
 .Ed
 .It Xo Ic server Ar address
 .Op Ic weight Ar weight-value