{AzureRecoveryServices} fixes #21000 (#21305)

fixes #21000

missing description for policyType as seen in the link below.
https://learn.microsoft.com/en-us/azure/templates/microsoft.recoveryservices/vaults/backuppolicies?pivots=deployment-language-arm-template#:~:text=int-,policyType,-%27Invalid%27%0A%27V1

Author: navba-MSFT

specification/recoveryservicesbackup/resource-manager/Microsoft.RecoveryServices/stable/2022-03-01/bms.json

@@ -5517,6 +5517,7 @@
           "type": "string"
         },
         "policyType": {
+          "description": "Type of backup policy type",
           "enum": [
             "Invalid",
             "V1",