In the supported platforms section on https://getfedora.org/en/workstation/prerelease/, there is a block "Linux | Available via DNF for Fedora | (More details)". The issue is that the link for "(More details)" goes to "how to make a usb key" but i think it should go to https://fedoraproject.org/wiki/DNF_system_upgrade like it does at the top. Running chrome on F24 (didn't test in FF, don't ask).