Add Action setting for build and deploy cargo doc

Author: termoshtt

.github/workflows/rust.yml

@@ -36,3 +36,17 @@ jobs:
           cargo tarpaulin --verbose --features=intel-mkl --out Xml --manifest-path=ndarray-linalg/Cargo.toml
       - name: Upload to codecov.io
         uses: codecov/codecov-action@v1
+
+  doc:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v2
+      - name: Generate code coverage
+        run: |
+          RUSTDOCFLAGS="--html-in-header katex-header.html" cargo doc --no-deps
+          mv target/doc public
+      - name: Deploy GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./public