update README

README.md

@@ -1,2 +1,50 @@
-# build-symfony-bundle
-Action for building and testing Symfony bundles.
+# Build Symfony Bundle Action
+
+This actions creates a blank Symfony project, installs the bundle in a `bundle` subdirectory and installs it with
+Composer to run its tests in a real application.
+
+## Usage
+
+```yaml
+- uses: ebitkov/build-symfony-bundle@v1
+  with:
+    # Whether to run the tests with PHPUnit
+    # Default: true
+    run-tests: ''
+
+    # PHP version to use.
+    # Default: 8.2
+    php-version:
+
+    # PHP extensions to install.
+    # String in CSV format.
+    # Default: 'mbstring, xml, ctype, iconv, intl, pdo, pdo_mysql, dom, filter, gd, json'
+    php-extensions: ''
+
+    # Additional options passed to Composer on installation.
+    # --no-interaction --no-progress --ansi are added automatically.
+    # Default: '--prefer-dist'
+    composer-options: ''
+
+    # Additional Composer dependencies to install.
+    # Runs after the main installation.
+    # Accepts flex aliases and full package names with version constraints.
+    # Multiple dependencies can be defined as space-separated (e.g. 'twig symfony/doctrine-bundle')
+    # Default: null
+    composer-additional-dependencies: ''
+
+    # Symfony version to use.
+    # Default: 6.3
+    symfony-version: ''
+
+    # Repository to install as a bundle.
+    # Mainly used internally for testing.
+    # Default: ${{ github.repository }}
+    repository: ''
+
+    # Bundle name as a Composer dependency: {vendor}/{package}.
+    # Useful, if your package name differs from your repository path.
+    # Mainly used internally for testing.
+    # Default: ${{ github.repository }}
+    bundle-name:
+```