[Doc] Modify transaction doc.
## Motivation
Modify transaction doc.
Now transaction is production ready, so delete Developer Preview.
---
id: transactions-api
-title: Transactions API (Developer Preview)
+title: Transactions API
sidebar_label: Transactions API
---
-All messages in a transaction is available only to consumers after the transaction is committed. If a transaction is aborted, all the writes and acknowledgments in this transaction rollback.
-
-Currently, Pulsar transaction is a developer preview feature. It is disabled by default. You can enable the feature and use transactions in your application in development environment.
+All messages in a transaction are available only to consumers after the transaction has been committed. If a transaction has been aborted, all the writes and acknowledgments in this transaction roll back.
## Prerequisites
1. To enable transactions in Pulsar, you need to configure the parameter in the `broker.conf` file.
