update "principles" link
the old principles info has been put into an "about" page on the faircoop website https://fair.coop/en/about-us/about and links need to be updated where they refer to the 2017 site
the old principles info has been put into an "about" page on the faircoop website https://fair.coop/en/about-us/about and links need to be updated where they refer to the 2017 site