REL-1274686: Update README.md to reference docs

Author: zachtepper

README.md

@@ -57,3 +57,16 @@ Artifacts/
 - `SampleRap.dll` — the main .NET assembly (agents, event handlers, services)
 - The compiled `SampleRap.CustomPage` ASP.NET MVC application (zipped as a custom page)
 - `application.xml` — the Relativity application schema defining the app's components
+
+## Documentation
+
+This repository includes comprehensive documentation for RAP Builder under the [`Documentation/`](Documentation/) folder. Start at [Documentation/README.md](Documentation/README.md) for an overview and links to additional guides:
+
+| Guide | Description |
+| ----- | ----------- |
+| [Getting Started](Documentation/getting-started.md) | Install RAP Builder and build your first RAP. |
+| [CLI Reference](Documentation/cli-reference.md) | Complete reference for all command-line arguments. |
+| [Configuration Reference](Documentation/configuration-reference.md) | Schema details for `build.xml` and `application.xml`. |
+| [Validation and Errors](Documentation/validation-and-errors.md) | Understanding validation output, error messages, and SDK checks. |
+| [Troubleshooting](Documentation/troubleshooting.md) | Common issues and solutions. |
+| [Migration Guide](Documentation/migration-guide.md) | Migrate from manual packaging or Publish to Relativity Tool. |