Documentation: git-send-email: fix submission port number

The current documentation confuses non-standard SSL smtp port 465 with
submission port 587 (RFC 4406). This patch just changes the referenced
number.

Signed-off-by: Wesley J. Landaker <wjl@icecavern.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-send-email.txt

@@ -143,7 +143,7 @@ user is prompted for a password while the input is masked for privacy.
 --smtp-server-port=<port>::
 	Specifies a port different from the default port (SMTP
 	servers typically listen to smtp port 25 and ssmtp port
-	465); symbolic port names (e.g. "submission" instead of 465)
+	465); symbolic port names (e.g. "submission" instead of 587)
 	are also accepted. The port can also be set with the
 	'sendemail.smtpserverport' configuration variable.