Documentation/config: add sendemail.tocmd to list preceding "See git-send-email(1)"

Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -3000,6 +3000,7 @@ sendemail.smtpPass::
 sendemail.suppresscc::
 sendemail.suppressFrom::
 sendemail.to::
+sendemail.tocmd::
 sendemail.smtpDomain::
 sendemail.smtpServer::
 sendemail.smtpServerPort::