Add github release action

.github/workflows/release.yml

@@ -0,0 +1,25 @@
+name: release
+on:
+  release:
+    types: [published]
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 12
+      - uses: subosito/flutter-action@v1
+        with:
+          channel: stable
+      - uses: bruceadams/[email protected]
+        id: release
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+      - run: |
+          echo '${{ secrets.CREDENTIALS_JSON }}' > $(which flutter | sed -r 's/bin\/flutter/.pub-cache\/credentials.json/')
+          export version=$(echo ${{ steps.release.outputs.tag_name }} | sed s/v//)
+          sed -i -r "s/version: .*/version: $version/" pubspec.yaml
+          sed -i "1s/^/## $version\n\n${{ steps.release.outputs.body }}\n\n/" CHANGELOG.md
+          flutter pub publish -f

.pubignore

@@ -0,0 +1,2 @@
+build/
+pigeon.dart

README.md

@@ -3,5 +3,6 @@
 A new flutter plugin project.
 
 ```
+mkdir android/src/main/java/qiuxiang/android_window -p
 flutter pub run pigeon --input lib/pigeon.dart --dart_out lib/pigeon.g.dart --java_out android/src/main/java/qiuxiang/android_window/Pigeon.java --java_package "qiuxiang.android_window"
-```
+```