doc: complete readme

README.md

@@ -1,3 +1,22 @@
 # setup-netcat
 
 GiHhub action to set up netcat on an ubuntu runner with the apt package manager
+
+usage example
+
+```yaml
+name: Main
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: runner
+    steps:
+      - name: Setup netcat tools
+        uses: RouxAntoine/setup-netcat@v1.0.0
+        id: setup-netcat
+```