chore: add workflow for gh-pages

.github/workflows/github-pages.yaml

@@ -0,0 +1,45 @@
+name: github pages
+
+on:
+  push:
+    branches:
+    - main  # Set a branch to deploy
+  pull_request:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-20.04
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0         # Fetch all history for .GitInfo and .Lastmod
+
+    - uses: actions/checkout@v2
+      with:
+        repository: google/docsy
+        path: docs/themes/docsy
+        submodules: true
+
+    - name: Setup Hugo
+      uses: peaceiris/actions-hugo@v2
+      with:
+        hugo-version: '0.87.0'
+        extended: true
+
+    - name: Setup Node
+      uses: actions/setup-node@v2
+      with:
+        node-version: '14'
+
+    - run: cd docs && npm install postcss postcss-cli autoprefixer
+
+    - run: cd docs && hugo --minify
+
+    - name: Deploy
+      uses: peaceiris/actions-gh-pages@v3
+      if: ${{ github.ref == 'refs/heads/main' }}
+      with:
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+        publish_dir: ./docs/public