docs: fix link to CONTRIBUTING.md in README
docs: fix link to CONTRIBUTING.md in README

zurb/foundation-sites,colin-marshall/foundation-sites,zurb/foundation-sites,abdullahsalem/foundation-sites,DaSchTour/foundation-sites,colin-marshall/foundation-sites,zurb/foundation-sites,denisahac/foundation-sites,abdullahsalem/foundation-sites,colin-marshall/foundation-sites,denisahac/foundation-sites,atmmarketing/foundation-sites,abdullahsalem/foundation-sites,zurb/foundation,DaSchTour/foundation-sites,zurb/foundation,atmmarketing/foundation-sites,zurb/foundation,atmmarketing/foundation-sites,denisahac/foundation-sites