doc: Advanced Cluster Differences and TF Core Upgrades (#2633)

* adv cluster differences doc updates

* Update docs/index.md

* Update index.md

* Update advanced_cluster.md

* Update advanced_cluster.md

* Update advanced_cluster.md

* Update cluster.md

* Update docs/index.md

Co-authored-by: maastha <122359335+maastha@users.noreply.github.com>

* Update docs/resources/cluster.md

Co-authored-by: maastha <122359335+maastha@users.noreply.github.com>

* Update docs/resources/cluster.md

Co-authored-by: Melissa Plunkett <themantissa@users.noreply.github.com>

* Update advanced_cluster.md

* Update cluster-to-advanced-cluster-migration-guide.md

---------

Co-authored-by: maastha <122359335+maastha@users.noreply.github.com>
Co-authored-by: Melissa Plunkett <themantissa@users.noreply.github.com>

Author: 3 people

docs/guides/cluster-to-advanced-cluster-migration-guide.md

@@ -6,6 +6,8 @@ page_title: "Migration Guide: Cluster to Advanced Cluster"
 
 **Objective**: This guide explains how to replace the `mongodbatlas_cluster` resource with the `mongodbatlas_advanced_cluster` resource. The data source(s) migration only requires [output changes](#output-changes) as data sources only read clusters.
 
+**Note**: In addition to below options, we are also actively exploring additional migration paths that do not involve Terraform State modifications. If interested to learn more or to test out directly please contact zuhair.ahmed@mongodb.com.
+
 ## Main Changes Between `mongodbatlas_cluster` and `mongodbatlas_advanced_cluster`
 
 1. Replication Spec Configuration: Supports different node types (electable, analytics, read_only) where hardware configuration can differ between node types.

docs/index.md

@@ -8,6 +8,8 @@ Use the navigation to the left to read about the available provider resources an
 You may want to consider pinning the [provider version](https://www.terraform.io/docs/configuration/providers.html#provider-versions) to ensure you have a chance to review and prepare for changes.
 Speaking of changes, see [CHANGELOG](https://github.com/mongodb/terraform-provider-mongodbatlas/blob/master/CHANGELOG.md) for current version information.  
 
+For the best experience, we recommend using the latest [HashiCorp Terraform Core Version](https://github.com/hashicorp/terraform). For more details see [HashiCorp Terraform Version Compatibility Matrix](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs#hashicorp-terraform-versionhttpswwwterraformiodownloadshtml-compatibility-matrix).
+
 ## Example Usage
 
 ```terraform

docs/resources/advanced_cluster.md

@@ -4,7 +4,7 @@
 
 More information on considerations for using advanced clusters please see [Considerations](https://docs.atlas.mongodb.com/reference/api/cluster-advanced/create-one-cluster-advanced/#considerations)
 
-~> **IMPORTANT:** The primary difference between [`mongodbatlas_cluster`](cluster) and [`mongodbatlas_advanced_cluster`](advanced_cluster) is that `mongodbatlas_advanced_cluster` supports multi-cloud clusters.  We recommend new users start with the `mongodbatlas_advanced_cluster` resource.  
+~> **IMPORTANT:** We recommend all new MongoDB Atlas Terraform users start with the [`mongodbatlas_advanced_cluster`](advanced_cluster) resource.  Key differences between [`mongodbatlas_cluster`](cluster) and [`mongodbatlas_advanced_cluster`](advanced_cluster) include support for [Multi-Cloud Clusters](https://www.mongodb.com/blog/post/introducing-multicloud-clusters-on-mongodb-atlas), [Asymmetric Sharding](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/advanced-cluster-new-sharding-schema), and [Independent Scaling of Analytics Node Tiers](https://www.mongodb.com/blog/post/introducing-ability-independently-scale-atlas-analytics-node-tiers).  For existing [`mongodbatlas_cluster`](cluster) resource users see our [Migration Guide](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/cluster-to-advanced-cluster-migration-guide). 
 
 -> **NOTE:** If Backup Compliance Policy is enabled for the project for which this backup schedule is defined, you cannot modify the backup schedule for an individual cluster below the minimum requirements set in the Backup Compliance Policy.  See [Backup Compliance Policy Prohibited Actions and Considerations](https://www.mongodb.com/docs/atlas/backup/cloud-backup/backup-compliance-policy/#configure-a-backup-compliance-policy).
 

docs/resources/cluster.md

@@ -2,8 +2,7 @@
 
 `mongodbatlas_cluster` provides a Cluster resource. The resource lets you create, edit and delete clusters. The resource requires your Project ID.
 
-~> **IMPORTANT:**
-<br> &#8226; New Users: If you are not already using `mongodbatlas_cluster` for your deployment we recommend starting with the [`mongodbatlas_advanced_cluster`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/advanced_cluster).  `mongodbatlas_advanced_cluster` has the same functionality as `mongodbatlas_cluster` but also supports multi-cloud clusters.  
+~> **IMPORTANT:** We recommend all new MongoDB Atlas Terraform users start with the [`mongodbatlas_advanced_cluster`](advanced_cluster) resource.  Key differences between [`mongodbatlas_cluster`](cluster) and [`mongodbatlas_advanced_cluster`](advanced_cluster) include support for [Multi-Cloud Clusters](https://www.mongodb.com/blog/post/introducing-multicloud-clusters-on-mongodb-atlas), [Asymmetric Sharding](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/advanced-cluster-new-sharding-schema), and [Independent Scaling of Analytics Node Tiers](https://www.mongodb.com/blog/post/introducing-ability-independently-scale-atlas-analytics-node-tiers).  For existing [`mongodbatlas_cluster`](cluster) resource users see our [Migration Guide](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/cluster-to-advanced-cluster-migration-guide). 
 
 -> **NOTE:** Groups and projects are synonymous terms. You may find group_id in the official documentation.