mention starttls(8)

src/etc/mail/README

@@ -1,11 +1,12 @@
-$OpenBSD: README,v 1.3 2005/11/10 10:55:23 jmc Exp $
+$OpenBSD: README,v 1.4 2007/12/11 16:43:14 millert Exp $
 
 This directory contains the configuration files for sendmail(8).
 The source for the .cf files lives in /usr/share/sendmail/cf.
 You should make changes in the corresponding .mc file and not edit
 the .cf files directly.  Useful information may be found in
 /usr/share/sendmail/README, /usr/share/sendmail/TUNING, and
-/usr/share/doc/smm/08.sendmailop/op.me.
+/usr/share/doc/smm/08.sendmailop/op.me.  For details on enabling
+encrypted SMTP, see the starttls(8) man page.
 
 Sendmail configuration files:
     submit.cf		Built from /usr/share/sendmail/cf/submit.mc.