CI: add documentation generation job

.github/workflows/documentation.yml

@@ -0,0 +1,48 @@
+name: Documentation
+on:
+  push:
+    branches: [ main ]
+
+jobs:
+  doc:
+    name: Documentation
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}/valib
+    permissions:
+      id-token: write
+      pages: write
+    steps:
+      - name: Install dependencies
+        if: startsWith(matrix.os, 'ubuntu')
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libasound2-dev
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ matrix.name }}-${{ matrix.cross-target }}
+      - uses: actions/checkout@v2
+      - name: Fetch all git history
+        run: git fetch --force --prune --tags --unshallow
+      - name: Set up Rust toolchain
+        uses: actions-rs/toolchain@v1
+      - name: Build documentation
+        run: cargo doc --all-features --no-deps
+      - name: Fix permissions
+        run: |
+          chmod -c -R +rX "target/doc" | while read line; do
+            echo "::warning title=Invalid file permissions automatically fixed::$line"
+          done
+      - name: Upload Pages artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: target/doc
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4 # or specific "vX.X.X" version tag for this action