Fix typo in docs
"X is short for Y" means X is the short version, whereas Y is the long one.
@@ -4,7 +4,7 @@ title: Messaging
sidebar_label: Messaging
---
-Pulsar is built on the [publish-subscribe](https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern) pattern (short for pub-sub). In this pattern, [producers](#producers) publish messages to [topics](#topics). [Consumers](#consumers) [subscribe](#subscription-modes) to those topics, process incoming messages, and send an acknowledgement when processing is complete.
+Pulsar is built on the [publish-subscribe](https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern) pattern (often abbreviated to pub-sub). In this pattern, [producers](#producers) publish messages to [topics](#topics). [Consumers](#consumers) [subscribe](#subscription-modes) to those topics, process incoming messages, and send an acknowledgement when processing is complete.
When a subscription is created, Pulsar [retains](concepts-architecture-overview.md#persistent-storage) all messages, even if the consumer is disconnected. Retained messages are discarded only when a consumer acknowledges that those messages are processed successfully.
