readme: improve

README.md

@@ -1,5 +1,25 @@
 # golangci-lint-action
 
-Work in progress
+![docker image](https://github.com/golangci/golangci-lint-action/workflows/docker%20image/badge.svg)
+
+Action that runs [golangci-lint](https://github.com/golangci/golangci-lint) and reports issues from linters.
+
+You can put `.github/workflows/lint.yml` with following contents:
+```yaml
+name: golangci
+on: [push]
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v1
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v0.0.2
+        with:
+          github_token: ${{ secrets.github_token }}
+
+```
 
 Based on [reviewdog action](https://github.com/reviewdog/action-golangci-lint).