Docs: `Unsubscribe` does not terminate Topic Actor

[eaba]

Please describe what you are trying to understand
https://getakka.net/articles/clustering/distributed-publish-subscribe.html#publish

...or you can explicitly remove entries with DistributedPubSubMediator.Unsubscribe

Actors are automatically removed from the registry when they are terminated. [ Actors are terminated if there are zero subscribers and no new subscriber within a given deadline - the default is 2 minutes. You can change the deadline by setting removed-time-to-live to a desired duration]

[Aaronontheweb]

This is correct - and this should be added.

We should also talk about when DeadLetters are produced in DistributedPubSub too, since that's not been clear - per the issues we've just recently resolved.

[eaba]

This is correct - and this should be added.

We should also talk about when DeadLetters are produced in DistributedPubSub too, since that's not been clear - per the issues we've just recently resolved.

Noted