chore: add readme file

README.md

@@ -1,3 +1,56 @@
-# JSR cli for node
+# JSR npm command line tool
 
-See https://jsr.io/ .
+The JSR npm CLI integrates JSR (JavaScript Registry) packages with npm-based projects, facilitating the use of JSR packages in environments that traditionally rely on npm. Learn more about JSR at [jsr.io](https://jsr.io).
+
+## Quick Start
+
+Add a JSR package to your project:
+
+```sh
+npx jsr add @package/name  # 'install' and 'i' are also supported
+```
+
+This command auto-updates your `package.json` and installs the package, automatically detecting and using your project's package manager.
+
+## How It Works
+
+The CLI creates or updates a `.npmrc` file in your project with:
+
+```
+@jsr:registry=https://npm.jsr.io
+```
+
+This line redirects npm to fetch JSR packages from the JSR registry instead of the default npm registry.
+
+Packages are added to `package.json` with an alias, mapping the JSR package name to the npm registry URL hosted by JSR, like so:
+
+```json
+{
+  "dependencies": {
+    "@luca/flag": "npm:@jsr/luca__flag@1"
+  }
+}
+```
+
+This ensures that the package is fetched from JSR when you run npm install commands.
+
+## Commands
+
+- `add`, `install`, `i`: Adds a JSR package to your project.
+- `remove`, `uninstall`, `r`: Remove a JSR package from your project.
+- `publish`: _(Coming Soon)_ Will support publishing npm modules directly to JSR.
+
+## Limitations
+
+- `jsr:` import specifiers are not supported.
+- Due to transpilation, the developer experience in editors might differ from native JSR usage.
+
+For the best developer experience and to fully leverage JSR's capabilities, consider environments with native JSR support like Deno.
+
+## Contributing
+
+We welcome contributions and feedback. Visit our GitHub repository to contribute or report issues.
+
+## License
+
+This CLI is available under the [MIT License](https://opensource.org/licenses/MIT).