Removes the provider setting and improves the Readme

Author: MrWolong

README.md

@@ -59,9 +59,76 @@ You can use this in your terraform template with the following steps.
 |------|-------------|
 | instance_ids    |     the IDs of Elasticsearch instance.     |
 
+## Notes
+From the version v1.2.0, the module has removed the following `provider` setting:
+
+```hcl
+provider "alicloud" {
+   version              = ">=1.56.0"
+   region               = var.region != "" ? var.region : null
+   configuration_source = "terraform-alicloud-modules/elasticsearch-instance"
+}
+```
+
+If you still want to use the `provider` setting to apply this module, you can specify a supported version, like 1.1.0:
+
+```hcl
+module "instance" {
+   source         = "terraform-alicloud-modules/elasticsearch-instance/alicloud"
+   version        = "1.1.0"
+   region         = "cn-beijing"
+   password       = "Your password"
+   data_node_amount = "2"
+   // ...
+}
+```
+
+If you want to upgrade the module to 1.2.0 or higher in-place, you can define a provider which same region with
+previous region:
+
+```hcl
+provider "alicloud" {
+	region = "cn-beijing"
+}
+module "instance" {
+   source         = "terraform-alicloud-modules/elasticsearch-instance/alicloud"
+   password       = "Your password"
+   data_node_amount = "2"
+	// ...
+}
+```
+or specify an alias provider with a defined region to the module using `providers`:
+
+```hcl
+provider "alicloud" {
+   region = "cn-beijing"
+   alias  = "bj"
+}
+module "instance" {
+   source           = "terraform-alicloud-modules/elasticsearch-instance/alicloud"
+   providers        = {
+      alicloud = alicloud.bj
+   }
+   password         = "Your password"
+   data_node_amount = "2"
+   // ...
+}
+```
+
+and then run `terraform init` and `terraform apply` to make the defined provider effect to the existing module state.
+
+More details see [How to use provider in the module](https://www.terraform.io/docs/language/modules/develop/providers.html#passing-providers-explicitly)
+
+## Terraform versions
+
+| Name | Version |
+|------|---------|
+| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 0.12.0 |
+| <a name="requirement_alicloud"></a> [alicloud](#requirement\_alicloud) | >= 1.56.0 |
+
 Authors
 -------
-Created and maintained by Guangfan Qu(@guangfanqu guangfan.qu@gmail.com)
+Created and maintained by Alibaba Cloud Terraform Team(terraform@alibabacloud.com)
 
 Reference
 ---------

main.tf

@@ -1,9 +1,3 @@
-provider "alicloud" {
-  version              = ">=1.56.0"
-  region               = var.region != "" ? var.region : null
-  configuration_source = "terraform-alicloud-modules/elasticsearch-instance"
-}
-
 #########################
 # Elasticsearch instance
 #########################

variables.tf

@@ -1,5 +1,5 @@
 variable "region" {
-  description = "The region used to launch this module resources."
+  description = "(Deprecated from version 1.2.0) The region used to launch this module resources."
   default     = ""
 }