(AzureCXP) fixes MicrosoftDocs/azure-docs#419671

Updated document by adding line no: 17,18

Author: PesalaPavan

articles/storage/blobs/scalability-targets-premium-block-blobs.md

@@ -14,4 +14,7 @@ ms.author: akashdubey
 
 A premium-performance block blob storage account is optimized for applications that use smaller, kilobyte-range objects. It's ideal for applications that require high transaction rates or consistent low-latency storage. Premium performance block blob storage is designed to scale with your applications. If your scenario requires that you deploy application(s) that require hundreds of thousands of requests per second or petabytes of storage capacity, contact Microsoft by submitting a support request in the [Azure portal](https://portal.azure.com/?#blade/Microsoft_Azure_Support/HelpAndSupportBlade).
 
+Premium Block Blob Storage only supports block blobs. Append blobs and page blobs are not supported in this storage tier.
+Premium block blob is available only in specific Azure regions — check regional availability before planning deployment.
+
 The service-level agreement (SLA) for Azure Storage accounts is available at [SLA for Storage Accounts](https://azure.microsoft.com/support/legal/sla/storage/v1_5/).