I've turned this into a Tor Browser ticket first, so the browser folks can tell us what the correct instructions are.
I'm guessing you need to go to about:config and toggle a thing, and also you need to go change something in noscript, which is harder than clicking on the noscript icon because there isn't one anymore. Maybe we want a faq entry on support.tpo instead, so more people can see it, and then relay-search can just link to that?
Postscript: I see in https://blog.torproject.org/new-release-tor-browser-907 that we have some instructions there. Is that text still right? If so, it sounds like the best plan is to turn that text into a support.tpo entry, and then tell future people (including relay-search) to link to that entry.