docs: fix typo in bug description in dropdownMenu
docs: fix typo in bug description in dropdownMenu

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