Add security note on astgenkey's manpage.

(closes issue #12373)
 Reported by: lmamane
 Patches: 
       20080406__bug12373.diff.txt uploaded by Corydon76 (license 14)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@113399 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/scripts/astgenkey.8

@@ -109,6 +109,21 @@ Run quietly.
 Don't encrypt the private key.
 .RE
 
+.SH SECURITY
+The keys are created, using the umask of the user running the command.
+To create the keys in a secure manner, you should check to ensure that
+your umask is first set to disallow the private key from being world-
+readable, such as with the following commands:
+
+.I umask 0066
+
+.I astgenkey yourkey
+
+And then make the key accessible to Asterisk (assuming you run it as
+user "asterisk").
+
+  chown asterisk /var/lib/asterisk/keys/yourname.*
+
 .SH FILES
 .I /var/lib/asterisk/keys
 .RS