rm force new of availability_zone (#1888)

* rm force new of availability_zone

* add changelog and doc

Author: lyu571

.changelog/1888.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+resource/tencentcloud_postgresql_instance: adjust `availability_zone` to unchangeable.
+```

tencentcloud/resource_tc_postgresql_instance.go

@@ -305,8 +305,7 @@ func resourceTencentCloudPostgresqlInstance() *schema.Resource {
 			"availability_zone": {
 				Type:        schema.TypeString,
 				Required:    true,
-				ForceNew:    true,
-				Description: "Availability zone. NOTE: If value modified but included in `db_node_set`, the diff will be suppressed.",
+				Description: "Availability zone. NOTE: This field could not be modified, please use `db_node_set` instead of modification. The changes on this field will be suppressed when using the `db_node_set`.",
 				DiffSuppressFunc: func(k, o, n string, d *schema.ResourceData) bool {
 					if o == "" {
 						return false
@@ -1183,9 +1182,9 @@ func resourceTencentCloudPostgresqlInstanceUpdate(d *schema.ResourceData, meta i
 
 	}
 
-	if d.HasChange("zone") {
-		log.Printf("[WARN] argument `zone` modified, skip process")
-
+	if d.HasChange("availability_zone") {
+		log.Printf("[WARN] argument `availability_zone` modified, skip process")
+		return fmt.Errorf("The `availability_zone` cannot be modified, please use `db_node_set` instead of it.")
 	}
 
 	if d.HasChange("db_kernel_version") {

website/docs/r/postgresql_instance.html.markdown

@@ -181,7 +181,7 @@ resource "tencentcloud_postgresql_instance" "test" {
 
 The following arguments are supported:
 
-* `availability_zone` - (Required, String, ForceNew) Availability zone. NOTE: If value modified but included in `db_node_set`, the diff will be suppressed.
+* `availability_zone` - (Required, String) Availability zone. NOTE: This field could not be modified, please use `db_node_set` instead of modification. The changes on this field will be suppressed when using the `db_node_set`.
 * `memory` - (Required, Int) Memory size(in GB). Allowed value must be larger than `memory` that data source `tencentcloud_postgresql_specinfos` provides.
 * `name` - (Required, String) Name of the postgresql instance.
 * `root_password` - (Required, String) Password of root account. This parameter can be specified when you purchase master instances, but it should be ignored when you purchase read-only instances or disaster recovery instances.