Update reference-collation-types.md

This limitation is confirmed by these ICM and work item.
ICM: https://portal.microsofticm.com/imp/v5/incidents/details/545458083/impact
Work Item: https://msdata.visualstudio.com/A365/_workitems/edit/3553326

Author: TsunehisaYamasaki

articles/synapse-analytics/sql/reference-collation-types.md

@@ -28,7 +28,7 @@ You can specify the default serverless SQL pool database collation at creation t
 To change the default collation for dedicated SQL pool database, update to the **Collation** field in the provisioning experience. For example, if you wanted to change the default collation to case sensitive, you would change the collation from `SQL_Latin1_General_CP1_CI_AS` to `SQL_Latin1_General_CP1_CS_AS`. 
 
 > [!NOTE]
-> Collation cannot be changed on an existing dedicated SQL pool database. If you need to have a different collation at the dedicated SQL pool level, create a new dedicated SQL pool with the required collation.
+> Collation cannot be changed on an existing dedicated SQL pool database. If you need to have a different collation at the dedicated SQL pool level, create a new dedicated SQL pool with the required collation. We can change Collation from Azure Portal. but, we can't change Collation from Synapse Studio. it's limitation for now.
 
 To change the default collation for a serverless SQL pool database, you can use ALTER DATABASE statement.