update README.md

Author: tomoyamachi

README.md

@@ -1 +1,38 @@
-# dockle-action
+# dockle-action
+
+GitHub Actions for [goodwithtech/dockle](https://github.com/goodwithtech/dockle)
+
+> Dockle - Container Image Linter for Security, Helping build the Best-Practice Docker Image, Easy to start
+
+Dockle helps you:
+
+1. Build Best Practice Docker images
+2. Build secure Docker images
+  - Checkpoints include CIS Benchmarks
+
+
+# Usage
+
+```yaml
+name: check
+on:
+  push:
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Build an image from Dockerfile
+        run: |
+          docker build -t built-image:scan .
+      - name: Run dockle
+        uses: goodwithtech/dockle-action@main
+        with:
+          image: 'built-image:scan'
+          format: 'list'
+          exit-code: '1'
+          exit-level: 'warn'
+          ignore: 'CIS-DI-0001,DKL-DI-0006'
+```