imap-send: use correct configuration variable in documentation

It's imap.pass (not imap.password).
Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-imap-send.txt

@@ -51,7 +51,7 @@ imap.host::
 imap.user::
 	The username to use when logging in to the server.
 
-imap.password::
+imap.pass::
 	The password to use when logging in to the server.
 
 imap.port::