Clarify blob secondary endpoint support

Author: linda33wj

articles/data-factory/connector-azure-blob-storage.md

@@ -8,7 +8,7 @@ ms.reviewer: craigg
 ms.service: data-factory
 ms.workload: data-services
 ms.topic: conceptual
-ms.date: 08/06/2019
+ms.date: 08/12/2019
 ms.author: jingwang
 
 ---
@@ -71,6 +71,9 @@ To use storage account key authentication, the following properties are supporte
 | connectionString | Specify the information needed to connect to Storage for the connectionString property. <br/>Mark this field as a SecureString to store it securely in Data Factory. You can also put account key in Azure Key Vault and pull the `accountKey` configuration out of the connection string. Refer to the following samples and [Store credentials in Azure Key Vault](store-credentials-in-key-vault.md) article with more details. |Yes |
 | connectVia | The [integration runtime](concepts-integration-runtime.md) to be used to connect to the data store. You can use Azure Integration Runtime or Self-hosted Integration Runtime (if your data store is in a private network). If not specified, it uses the default Azure Integration Runtime. |No |
 
+>[!NOTE]
+>Azure Blob secondary endpoint is not supported when using account key authentication. You can use the other authentication types.
+
 >[!NOTE]
 >If you were using "AzureStorage" type linked service, it is still supported as-is, while you are suggested to use this new "AzureBlobStorage" linked service type going forward.