docs: Add dualstack nlb scenario example.

website/docs/r/nlb_load_balancer.html.markdown

@@ -71,6 +71,66 @@ resource "alicloud_nlb_load_balancer" "default" {
 }
 ```
 
+DualStack Usage
+
+```terraform
+provider "alicloud" {
+  region = "cn-beijing"
+}
+
+variable "name" {
+  default = "tf-example"
+}
+
+variable "zone" {
+  default = ["cn-beijing-i", "cn-beijing-k", "cn-beijing-l"]
+}
+
+resource "alicloud_vpc" "vpc" {
+  vpc_name    = var.name
+  cidr_block  = "10.2.0.0/16"
+  enable_ipv6 = true
+}
+
+resource "alicloud_vswitch" "vsw" {
+  count                = 2
+  enable_ipv6          = true
+  ipv6_cidr_block_mask = "1${count.index}"
+  vswitch_name         = "vsw-${count.index}-for-nlb"
+  vpc_id               = alicloud_vpc.vpc.id
+  cidr_block           = "10.2.1${count.index}.0/24"
+  zone_id              = var.zone[count.index]
+}
+
+resource "alicloud_vpc_ipv6_gateway" "default" {
+  ipv6_gateway_name = var.name
+  vpc_id            = alicloud_vpc.vpc.id
+}
+
+resource "alicloud_nlb_load_balancer" "nlb" {
+  depends_on         = [alicloud_vpc_ipv6_gateway.default]
+  load_balancer_name = var.name
+  load_balancer_type = "Network"
+  address_type       = "Intranet"
+  address_ip_version = "DualStack"
+  ipv6_address_type  = "Internet"
+  vpc_id             = alicloud_vpc.vpc.id
+  cross_zone_enabled = false
+  tags = {
+    Created = "TF",
+    For     = "example",
+  }
+  zone_mappings {
+    vswitch_id = alicloud_vswitch.vsw[0].id
+    zone_id    = var.zone[0]
+  }
+  zone_mappings {
+    vswitch_id = alicloud_vswitch.vsw[1].id
+    zone_id    = var.zone[1]
+  }
+}
+```
+
 ## Argument Reference
 
 The following arguments are supported: