Update documentation text for the zoneBalance property (#15231)

* Fix public IP sku name and Tier property names

* remove required property to match NRP swagger spec

* update example file

* update zoneBalance help message

Co-authored-by: Bashar Gharaibeh <basharghar@live.com>

Author: basharg

specification/compute/resource-manager/Microsoft.Compute/stable/2021-04-01/compute.json

@@ -13487,7 +13487,7 @@
         },
         "zoneBalance": {
           "type": "boolean",
-          "description": "Whether to force strictly even Virtual Machine distribution cross x-zones in case there is zone outage."
+          "description": "Whether to force strictly even Virtual Machine distribution cross x-zones in case there is zone outage. zoneBalance property can only be set if the zones property of the scale set contains more than one zone. If there are no zones or only one zone specified, then zoneBalance property should not be set."
         },
         "platformFaultDomainCount": {
           "type": "integer",