ci: Build the documentation book in CI

.github/workflows/book.yaml

@@ -0,0 +1,44 @@
+name: Book
+
+on:
+  push:
+    branches: [trunk]
+  pull_request:
+    branches: [trunk]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: pages
+  cancel-in-progress: false
+
+jobs:
+  build:
+    name: Build book
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: peaceiris/actions-mdbook@v2
+        with:
+          mdbook-version: latest
+      - name: Build
+        run: mdbook build
+      - uses: actions/upload-pages-artifact@v3
+        with:
+          path: target/doc
+
+  deploy:
+    name: Deploy to GitHub Pages
+    if: github.event_name == 'push'
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - uses: actions/deploy-pages@v4
+        id: deployment

book.toml

@@ -1,7 +1,6 @@
 [book]
 authors = ["Travis Gockel"]
 language = "en"
-multilingual = false
 src = "doc"
 
 [build]