reference to guide

Author: lantoli

README.md

@@ -30,6 +30,8 @@ atlas plugin list
 
 ### Usage
 
+You can find more information in the [Migration Guide: Cluster to Advanced Cluster](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/cluster-to-advanced-cluster-migration-guide).
+
 **Note**: In order to use the **Preview for MongoDB Atlas Provider 2.0.0** of `mongodbatlas_advanced_cluster`, you need to set the environment variable `MONGODB_ATLAS_PREVIEW_PROVIDER_V2_ADVANCED_CLUSTER` to `true`.
 
 If you want to convert a Terraform configuration from `mongodbatlas_cluster` to `mongodbatlas_advanced_cluster`, use the following command: