fix another parameter error

Author: pdiniz13

nestedtemplates/external-lb.json

@@ -17,6 +17,10 @@
         "vnetId": {
             "type": "String",
             "defaultValue": ""
+        },
+        "zookeeperNetName": {
+            "defaultValue": "",
+            "type": "String"
         }
     },
     "variables": {},

template.json

@@ -427,6 +427,9 @@
                     "lbId": {
                         "value": "[variables('lbId')]"
                     },
+                    "vnetId": {
+                        "value": "[variables('vnetId')]"
+                    },
                     "zookeeperNetName": {
                         "value": "[parameters('zookeeperNetName')]"
                     }