Update understanding-billing.md

Specify the type of file share instead of type of disk.

Author: tachyontec

articles/storage/files/understanding-billing.md

@@ -19,7 +19,7 @@ Azure Files has multiple pricing models including provisioned and pay-as-you-go
 
 - **Provisioned billing models**: In a provisioned billing model, the primary costs of the file share are based on the amount of storage, IOPS (input and output operations per second), and throughput you provision when you create or update your file share, regardless of how much you use. Azure Files has two different provisioned models *provisioned v2* and *provisioned v1*.
     - **Provisioned v2**: In the provisioned v2 model, you have the ability to separately provision storage, IOPS, and throughput, although we provide a recommendation for you to help you with first time provisioning.
-    - **Provisioned v1**: In the provisioned v1 model, you provision the amount of storage you need for the share while IOPS and throughput are determined based on how much storage you provision. The provisioned v1 model for Azure Files is only available for SSD file shares.
+    - **Provisioned v1**: In the provisioned v1 model, you provision the amount of storage you need for the share while IOPS and throughput are determined based on how much storage you provision. The provisioned v1 model for Azure Files is only available for Premium file shares.
 
 - **Pay-as-you-go billing model**: In a pay-as-you-go model, the cost of the file share is based on how much you use the share, in the form of used storage, transaction, and data transfer costs. The pay-as-you-go model for Azure Files is only available for HDD file shares. We recommend using the provisioned v2 model for new HDD file share deployments.