That would be NIP-05: https://nostrcompass.org/en/topics/nip-05/

Le Monde adds a text file at https://lemonde.fr/.well-known/nostr.json with the npubs (NOSTR public keys) of every person that they certify as trusted.

So then you go around using "maelito@lemonde.fr" and anyone can find your public key on the official Le Monde site, verify that you are indeed someone associated to that domain.