Document support for the new 'U' flag, which was implemented back in March

as revision 1.64 of newsyslog.c.  I plan to MFC these changes next week.

MFC after:	1 week

usr.sbin/newsyslog/newsyslog.8

@@ -17,7 +17,7 @@
 .\" the suitability of this software for any purpose.  It is
 .\" provided "as is" without express or implied warranty.
 .\"
-.Dd March 02, 2003
+.Dd March 08, 2003
 .Dt NEWSYSLOG 8
 .Os
 .Sh NAME
@@ -312,6 +312,13 @@ log file using
 .It Sy N
 indicates that there is no process which needs to be signalled
 when this log file is rotated.
+.It Sy U
+indicates that the file specified by
+.Ar path_to_pid_file
+will contain the id for a process group, instead of a process.
+This option also requires that the first line in that file must
+be a negative value, to distinguish it from a value for a
+process id.
 .It Sy W
 if used with the
 .Sy Z
@@ -341,7 +348,9 @@ field when you need to specify any of the following fields.
 .El
 .It Ar path_to_pid_file
 This optional field specifies the file name to read to find the daemon
-process id.
+process id, or to find a process group id if the
+.Sy U
+flag was specified.
 If this field is present, a
 .Ar signal_number
 is sent the process id contained in this file.
@@ -354,10 +363,12 @@ flag has been specified.
 This field must start with "/" in order to be recognized
 properly.
 .It Ar signal_number
-This optional field specifies
-the signal number will be sent to the daemon process.
-By default
-a SIGHUP will be sent.
+This optional field specifies the signal number that will be sent
+to the daemon process (or to all processes in a process group, if
+the
+.Sy U
+flag was specified).
+If this field is not present, then a SIGHUP signal will be sent.
 .El
 .Sh OPTIONS
 The following options can be used with