add github action

.github/workflows/pub.yml

@@ -0,0 +1,33 @@
+name: Build & Pub
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@v1
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+      - name: Build
+        run: |
+          npm run init
+          npm run build
+      - name: Commit files
+        run: |
+          cd _book
+          git config --global user.email "action@github.com"
+          git config --global user.name "GitHub Action"
+          git init
+          git add .
+          git commit -m "GitHub Action build docs" -a
+      - name: Push changes
+        uses: ad-m/github-push-action@master
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          directory: docs