[Doc] Lack of understanding "Namespace change events" for Zookeeper

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### What issue do you find in Pulsar docs?

It is written that using namespace change events :

> * Avoid using ZooKeeper and introduce more loads to ZooKeeper.

https://pulsar.apache.org/docs/4.0.x/concepts-multi-tenancy/#namespace-change-events-and-topic-level-policies

I don't understand the purpose of this : is it use more or less Zookeeper ?

Best regards,
Guillaume

### What is your suggestion?

Correct description

### Any reference?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start with the “Namespace change events and topic-level policies” section in the Pulsar 4.0.x multi-tenancy documentation and verify how namespace change events affect ZooKeeper usage. Clarify whether the feature increases or reduces ZooKeeper load, then update the description so its purpose and effect are unambiguous.

Written by the indexing model from the issue text.