docs(readme): add usage instructions for changelog generator

- Introduce README with instructions for generating Debian-style changelogs
- Provide example command and optional arguments explanation
- Highlight dependencies and output behavior

README.md

@@ -0,0 +1,24 @@
+# Debian Changelog Generator
+
+## External Usage
+
+This repository provides a one-liner to generate a Debian-style changelog using `git-cliff`.
+
+## Quick Usage
+
+You can run the generator directly from the URL:
+
+```bash
+curl -s https://git.0xmax42.io/actions/deb-changelog-action/raw/branch/main/run.sh | bash -s -- \
+  --tag v2.9.1 \
+  --package_name my-package \
+  --author_name "John Doe" \
+  --author_email "john@example.com"
+```
+
+Optional arguments:
+
+* `--output_file debian/changelog` (default)
+* `--cliff_config path/to/custom.toml`
+
+> ⚠️ This will clone the action to a temporary directory, install `git-cliff`, and write the changelog into your current working directory.