chore: update README.md

Author: actions-user

README.md

@@ -2,8 +2,11 @@
 
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 <a href="https://cpco.io/homepage"><img src="https://github.com/cloudposse/terraform-aws-documentdb-cluster/blob/main/.github/banner.png?raw=true" alt="Project Banner"/></a><br/>
-    <p align="right">
-<a href="https://github.com/cloudposse/terraform-aws-documentdb-cluster/releases/latest"><img src="https://img.shields.io/github/release/cloudposse/terraform-aws-documentdb-cluster.svg?style=for-the-badge" alt="Latest Release"/></a><a href="https://github.com/cloudposse/terraform-aws-documentdb-cluster/commits"><img src="https://img.shields.io/github/last-commit/cloudposse/terraform-aws-documentdb-cluster.svg?style=for-the-badge" alt="Last Updated"/></a><a href="https://cloudposse.com/slack"><img src="https://slack.cloudposse.com/for-the-badge.svg" alt="Slack Community"/></a></p>
+
+
+<p align="right"><a href="https://github.com/cloudposse/terraform-aws-documentdb-cluster/releases/latest"><img src="https://img.shields.io/github/release/cloudposse/terraform-aws-documentdb-cluster.svg?style=for-the-badge" alt="Latest Release"/></a><a href="https://github.com/cloudposse/terraform-aws-documentdb-cluster/commits"><img src="https://img.shields.io/github/last-commit/cloudposse/terraform-aws-documentdb-cluster.svg?style=for-the-badge" alt="Last Updated"/></a><a href="https://cloudposse.com/slack"><img src="https://slack.cloudposse.com/for-the-badge.svg" alt="Slack Community"/></a><a href="https://cloudposse.com/support/"><img src="https://img.shields.io/badge/Get_Support-success.svg?style=for-the-badge" alt="Get Support"/></a>
+
+</p>
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 <!--
@@ -297,7 +300,36 @@ In general, PRs are welcome. We follow the typical "fork-and-pull" Git workflow.
  5. **Push** your work back up to your fork
  6. Submit a **Pull Request** so that we can review your changes
 
-**NOTE:** Be sure to merge the latest changes from "upstream" before making a pull request!
+**NOTE:** Be sure to merge the latest changes from "upstream" before making a pull request!## Running Terraform Tests
+
+We use [Atmos](https://atmos.tools) to streamline how Terraform tests are run. It centralizes configuration and wraps common test workflows with easy-to-use commands.
+
+All tests are located in the [`test/`](test) folder.
+
+Under the hood, tests are powered by Terratest together with our internal [Test Helpers](https://github.com/cloudposse/test-helpers) library, providing robust infrastructure validation.
+
+Setup dependencies:
+- Install Atmos ([installation guide](https://atmos.tools/install/))
+- Install Go [1.24+ or newer](https://go.dev/doc/install)
+- Install Terraform or OpenTofu
+
+To run tests:
+
+- Run all tests:  
+  ```sh
+  atmos test run
+  ```
+- Clean up test artifacts:  
+  ```sh
+  atmos test clean
+  ```
+- Explore additional test options:  
+  ```sh
+  atmos test --help
+  ```
+The configuration for test commands is centrally managed. To review what's being imported, see the [`atmos.yaml`](https://raw.githubusercontent.com/cloudposse/.github/refs/heads/main/.github/atmos/terraform-module.yaml) file.
+
+Learn more about our [automated testing in our documentation](https://docs.cloudposse.com/community/contribute/automated-testing/) or implementing [custom commands](https://atmos.tools/core-concepts/custom-commands/) with atmos.
 
 ### 🌎 Slack Community