Nostr Idea: Disappearing Notes

1. If a relay can be set up that wipes out particular events like notes in X period (say 1 month) of time, it increases privacy on Nostr.

2. As it's not a blockchain any post shouldn't be there forever. Just like Telegram or Signal, having the option of disappearing messages (notes) will be a great feature.

3. This also makes that relay efficient as all old notes is wiped out periodically keeping the total size of relay limited enough so it becomes more cost efficient.