add GitHub Actions workflow to deploy mdBook

Author: rex-schilasky

.github/workflows/deploy-docs.yml

@@ -0,0 +1,28 @@
+name: Deploy mdBook to GitHub Pages
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Install mdBook
+        uses: peaceiris/actions-mdbook@v1
+        with:
+          mdbook-version: 'latest'
+
+      - name: Build the book
+        run: mdbook build docs
+
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./docs/book