added note that /mail/lib/whitelist must be append only

-Steve

Reference: /n/sources/patch/applied/smtp-man1
Date: Tue Jul 20 11:51:57 CES 2004

--- /sys/man/8/smtp	Tue Jul 20 11:51:14 2004
+++ /sys/man/8/smtp	Tue Jul 20 11:51:12 2004
@@ -115,7 +115,8 @@
 .B -g
 turns on grey/white list processing.  All mail is rejected (with a
 retry code) unless the sender's IP address is on the whitelist,
-.BR /mail/lib/whitelist .
+.BR /mail/lib/whitelist ,
+an append only file.
 Addresses can be added to the whitelist by the administrator.  However,
 the usual way for addresses to be added is by smtpd itself.  Whenever,
 a message is received and the sender's address isn't on the whitelist,