Here it was!
But can't figure out how to implement this with cloudflare tunnel.
Discussion
If you have a github account, you could request this to be added to the "Relay Document" as served by strfry and reference this: https://github.com/nostr-protocol/nips/blob/23d605140bdbe6ccc43c6ebbcd2412a05ff262fa/11.md?plain=1#L259-L268
Hope it helps. :)
Thanks. I thought about it and also asked in the telegram group! We'll see if I get some response there first.