Add priority to VM Scale Set VM profile.

specification/compute/resource-manager/Microsoft.Compute/stable/2017-12-01/compute.json

@@ -5957,6 +5957,18 @@
         "licenseType": {
           "type": "string",
           "description": "Specifies that the image or disk that is being used was licensed on-premises. This element is only used for images that contain the Windows Server operating system. <br><br> Possible values are: <br><br> Windows_Client <br><br> Windows_Server <br><br> If this element is included in a request for an update, the value must match the initial value. This value cannot be updated. <br><br> For more information, see [Azure Hybrid Use Benefit for Windows Server](https://docs.microsoft.com/azure/virtual-machines/virtual-machines-windows-hybrid-use-benefit-licensing?toc=%2fazure%2fvirtual-machines%2fwindows%2ftoc.json) <br><br> Minimum api-version: 2015-06-15"
+        },
+        "priority": {
+          "type": "string",
+          "description": "Specifies the priority for the virtual machines in the scale set. <br><br>Minimum api-version: 2017-10-30-preview",
+          "enum": [
+            "Regular",
+            "Low"
+          ],
+          "x-ms-enum": {
+            "name": "VirtualMachinePriorityTypes",
+            "modelAsString": true
+          }
         }
       },
       "description": "Describes a virtual machine scale set virtual machine profile."