I would say the first commit
Or the first readme:
readme:

GitHub
basic server relay code. · nostr-protocol/nostr@6158017
a truly censorship-resistant alternative to Twitter that has a chance of working - basic server relay code. · nostr-protocol/nostr@6158017
GitHub
a readme explaining the idea. · nostr-protocol/nostr@bdeb03a
a truly censorship-resistant alternative to Twitter that has a chance of working - a readme explaining the idea. · nostr-protocol/nostr@bdeb03a