#358 Add link to mailing list login page

[Tyler Akins]

I have a low traffic mailing list and it received an email that needed approval. I forgot my password to the list. The email sent to administrators says to go to https://lists.sourceforge.net/lists/admindb/LIST_NAME_HERE and that page does not have a "forgot password?" style of link. Searching the targets of the links on that page did not reveal anything helpful and I ended up learning mostly about Mailman.

It would be very helpful to link to https://sourceforge.net/p/php-pdb/admin/mailman/ from the login page for mailman.