bug#3086: supercite mailing lists

[jidanni]

supercite Info says to use sc-submit-bug-report, but that gives

> Diagnostic-Code: X-Postfix; host mx10.gnu.org[199.232.76.166] said: 
> 550-Callout
>     verification failed: 550-550-Callout verification failed: 550-550-550 
> 5.1.1
>     <supercite-help@python.org>: Recipient address rejected: 550 550 User
>     unknown (in reply to RCPT TO command)
>
>
> From: jidanni@jidanni.org
> Subject: list not archived
> To: bug-supercite@gnu.org
>
> I don't see this list on http://lists.gnu.org/archive/html/ .

And then there's the (info "(sc)The Supercite Mailing List")
which doesn't mention where it is archived.

Perhaps eliminate all traces of these in the documentation, if they
don't exist.