Add GitHub Actions workflow for Jekyll build and deploy

.github/workflows/jekyll.yml

@@ -0,0 +1,31 @@
+name: Build and Deploy Jekyll Site
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.1
+
+      - name: Install dependencies
+        run: bundle install
+
+      - name: Build site with Jekyll
+        run: bundle exec jekyll build
+
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./_site