add a RELEASE.md doc

RELEASE.md

@@ -0,0 +1,56 @@
+# Release Process
+
+This document outlines the process for creating new releases of Railpack.
+
+## Creating a New Release
+
+1. Determine the new version number following [Semantic
+   Versioning](https://semver.org/) principles:
+
+   - MAJOR version for incompatible API changes
+   - MINOR version for backwards-compatible functionality additions
+   - PATCH version for backwards-compatible bug fixes
+
+2. Create and push a new tag with the version number:
+
+   ```bash
+   git tag v1.2.3  # Replace with your version number
+   git push origin --tags
+   ```
+
+3. The [release
+   workflow](https://github.com/railwayapp/railpack/actions/workflows/release.yml)
+   will automatically:
+   - Build and publish the frontend Docker image to
+     [GHCR](https://github.com/orgs/railwayapp/packages?repo_name=railpack)
+   - Create a GitHub release with changelog
+   - Build and attach binaries for multiple platforms
+
+## Release Artifacts
+
+### Frontend Docker Image
+
+The frontend Docker image is published to GitHub Container Registry (GHCR) with
+the following tags:
+
+- `ghcr.io/railpack/railpack-frontend:latest` (on default branch)
+- `ghcr.io/railpack/railpack-frontend:v1.2.3` (specific version)
+- `ghcr.io/railpack/railpack-frontend:1.2` (minor version)
+
+The image is built for both `linux/amd64` and `linux/arm64` platforms.
+
+### Binary Releases
+
+The release workflow automatically builds and attaches binaries for multiple
+platforms to the GitHub release.
+
+## Verifying a Release
+
+After pushing a tag:
+
+1. Check the [Actions tab](https://github.com/railwayapp/railpack/actions) to
+   monitor the release workflow
+2. Verify the [GitHub release](https://github.com/railwayapp/railpack/releases)
+   is created with the correct artifacts
+3. Confirm the frontend Docker image is available in the [package
+   registry](https://github.com/orgs/railwayapp/packages?repo_name=railpack)