Update availability group improvement

Author: MikeRayMSFT

docs/sql-server/what-s-new-in-sql-server-2022.md

@@ -61,8 +61,8 @@ The following sections provide an overview of these features.
 |:---|:---|
 | Link to Azure SQL Managed Instance | Connect your SQL Server instance to Azure SQL Managed Instance. See [Link feature for Azure SQL Managed Instance (preview)](/azure/azure-sql/managed-instance/managed-instance-link-feature-overview). To experience this feature you can [register here](https://aka.ms/mi-link-2022-signup).|
 |Contained availability group | Create an Always On availability group that:<br/>- Manages its own metadata objects (users, logins, permissions, SQL Agent jobs etc.) at the availability group level in addition to the instance level. <br/>- Includes specialized contained system databases within the availability group. For more information, see [What is a contained availability group?](../database-engine/availability-groups/windows/contained-availability-groups-overview.md)|
-|Distributed availability group |- Changing `REQUIRED_SYNCHRONIZED_SECONDARIES_TO_COMMIT` is supported. For more information, visit [ALTER AVAILABILITY GROUP (Transact-SQL)](../t-sql/statements/alter-availability-group-transact-sql.md)<br/>- Now using multiple TCP connections for better network bandwidth utilization across a remote link with long tcp latencies.|
-| Improved availability groups | Parallel redo and improvements for readable secondary replicas. |
+|Distributed availability group |- Changing `REQUIRED_SYNCHRONIZED_SECONDARIES_TO_COMMIT` is supported. For more information, visit [ALTER AVAILABILITY GROUP (Transact-SQL)](../t-sql/statements/alter-availability-group-transact-sql.md)<br/> - Now using multiple TCP connections for better network bandwidth utilization across a remote link with long tcp latencies.|
+| Improved availability groups | - ParallelRedoThreadPool : Instance level thread pool shared with all databases having redo work. With this, each database can take the benefit of parallel redo. Limited to max 100 threads limit earlier. <br/> - Parallel Redo Batch Redo - Redo of log records are batched under one latch improving speed. This helps both, catchup redo and crash recovery redo. |
 | Improved backup metadata | `backupset` system table returns last valid restore time. See [backupset (Transact-SQL)](../relational-databases/system-tables/backupset-transact-sql.md).|
 
 ## Security