Update support-for-fci.md

No support for automatic backup or PITR

Author: MikeRayMSFT

docs/sql-server/azure-arc/support-for-fci.md

@@ -48,7 +48,8 @@ The portal displays the databases on the SQL Server instance.
 
 - All the Windows and SQL Server instances that are part of the failover clustering should be in same resource group.
 - Always On availability groups on a failover cluster instance aren't supported for Azure Arc-enabled SQL Server at this time.
+- Automated backups and point-in-time restore is not supported for failover cluster instances at this time.
 
 ## Related tasks
 
-- [View SQL Server databases - Azure Arc](view-databases.md)
+- [View SQL Server databases - Azure Arc](view-databases.md)