logger.1: Clarify -i flag

The PID of the logger process is always recorded along with the move from RFC
3164 to RFC 5424.

Indicate the -i flag is a no-op now in logger(1).

Related to a similary change in syslog.3

Reported by:	danfe@
Approved by:	manpages (0mp)
Fixes:	94eb6c42ab
Differential Revision:	https://reviews.freebsd.org/D34578

usr.bin/logger/logger.1

@@ -28,7 +28,7 @@
 .\"	@(#)logger.1	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd December 5, 2017
+.Dd March 16, 2022
 .Dt LOGGER 1
 .Os
 .Sh NAME
@@ -73,6 +73,7 @@ tries to send the message to all addresses.
 .It Fl i
 Log the process id of the logger process
 with each line.
+This flag is ignored and the process id is always logged.
 .It Fl s
 Log the message to standard error, as well as the system log.
 .It Fl f Ar file