Updated the SA name

Author: vikasnav

101-simple-windows-vm/azuredeploy.json

@@ -7,7 +7,7 @@
             "metadata": {
                 "description": "Unique DNS Name for the Storage Account where the Virtual Machine's disks will be placed."
             },
-             "defaultValue": "[concat('sa',resourceGroup().id)]"
+             "defaultValue": "[substring(concat('vm',uniquestring(replace(resourceGroup().Id,'-',''))),0,8)]"
         },
         "vmName": {
             "type": "string",