NIP-05 is the name of the tech https://github.com/nostr-protocol/nips/blob/master/05.md

You basically write a json file (code is at git, you have to put your username and npubkey), then publish it on your domain, set proper CORS handlers (I couldn't do this wen I did), and finally update the info in any client (to me worked updating through https://coracle.social even though I couldn't manage to set the CORS stuff).