[ReleasePR relay] Azure Relay - added missing publicNetworkAccess at NetwrokRuleSet level (#2648)

Create to sync Azure/azure-rest-api-specs#20745
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/main...azure-sdk:sdkAuto/relay?expand=1)

Author: msftbot[bot]

schemas/2021-11-01/Microsoft.Relay.json

@@ -792,6 +792,22 @@
             }
           ],
           "description": "List of IpRules"
+        },
+        "publicNetworkAccess": {
+          "oneOf": [
+            {
+              "type": "string",
+              "enum": [
+                "Enabled",
+                "Disabled",
+                "SecuredByPerimeter"
+              ]
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "This determines if traffic is allowed over public network. By default it is enabled."
         }
       },
       "description": "NetworkRuleSet properties"