Broadcast PeerInfo message on new Subscription to Topic

[justin0mcateer]

GossipSub provides an event when a new peer subscribes to a topic. It seems that peer discovery time would be reduced significantly if peers broadcast their PeerInfo immediately (perhaps with a short backoff) when they see new peers joining the peer discovery topic.

I was thinking to implement a small patch that would add this behavior. Can anyone see any reason why this wouldn't be beneficial or any other reason to not do this?