Link to mailing lists is broken, please replace "http://www.trusteddomain.org" by "https://openarc.org" in README.md

[rotdrop]

Actually, the pages at

http://www.trusteddomain.org

really have no hints to mailing lists whatsoever. Asking Google (ouch) I stumbled over https://openarc.org which seemingly has the mailing lists openarc-users etc.

The README.md lists http://www.trusteddomain.org as entry point to the mailing-lists.

Could the maintainers please update the README.md and please clarify whether or not the mailing lists at openarc.org are the correct ones?

Kind thanks

Claus