[mew-int 2862] mew-config-alist is not documented to support bcc

The mew-config-alist variable supports the bcc key, but that fact is not
documented.  This patch corrects the documentation.

		    -Mike


diff --git a/mew-vars2.el b/mew-vars2.el
index 7124857..f3350cb 100644
--- a/mew-vars2.el
+++ b/mew-vars2.el
@@ -921,7 +921,7 @@ to messages and puts them to your mailbox, configure as follows:

 Currently, the following keys are supported:
 name, user, mail-domain,
-cc, fcc, dcc, reply-to, organization, header-alist, proto,
+cc, bcc, fcc, dcc, reply-to, organization, header-alist, proto,
 smtp-server, smtp-port, smtp-ssh-server, smtp-ssl, smtp-ssl-port,
 smtp-user, smtp-auth-list,
 smtp-msgid-user, smtp-msgid-domain, smtp-helo-domain, smtp-mail-from,