ci: add docs build to GHA (#897)

Restoring the docs build after we lost it with Travis.

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

.github/workflows/docs.yml

@@ -0,0 +1,91 @@
+name: Docs
+
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  apidocs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: mattnotmitt/doxygen-action@v1
+        with:
+          doxyfile-path: ./docs/Doxyfile
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: api-docs
+          path: html
+
+  gitbook:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-node@v3
+        with:
+          node-version: 16
+
+      - uses: awalsh128/cache-apt-pkgs-action@v1
+        with:
+          packages: calibre calibre-bin libxss1 libasound2
+          version: 1
+
+      - name: Install JS requirements
+        working-directory: book
+        run: |
+          npm install
+
+      - name: Build book
+        working-directory: book
+        run: |
+          npx gitbook build . public
+          npx gitbook pdf . public/cli11.pdf
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: gitbook
+          path: book/public
+
+  pages:
+    runs-on: ubuntu-latest
+    needs: [apidocs, gitbook]
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    if: >
+      success()
+      && github.ref == 'refs/heads/main'
+      && github.repository == 'CLIUtils/CLI11'
+    steps:
+      - uses: actions/configure-pages@v3
+        id: pages
+
+      - uses: actions/download-artifact@v3
+        with:
+          name: api-docs
+          path: _site
+
+      - uses: actions/download-artifact@v3
+        with:
+          name: gitbook
+          path: _site/book
+
+      - uses: actions/upload-pages-artifact@v1
+
+      - uses: actions/deploy-pages@v2
+        id: deployment

book/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "cli11-gitbook",
+  "version": "1.0.0",
+  "dependencies": {
+    "gitbook-cli": "2.2.0",
+    "gitbook-plugin-hints": "^1.0.2",
+    "gitbook-plugin-include-codeblock": "^3.2.2",
+    "gitbook-plugin-term": "^0.5.1",
+    "svgexport": ">=0.4.2"
+  },
+  "scripts": {
+    "postinstall": "npx gitbook fetch 3.2.3 && npx gitbook install"
+  }
+}