Automate docs deployment

.github/workflows/docs.yml

@@ -0,0 +1,31 @@
+name: Build and deploy documentation
+'on':
+  push:
+    branches:
+      - main
+jobs:
+  build_docs:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      - name: Install pipenv
+        run: |
+          python -m pip install --upgrade pip
+          pip install pipenv
+      - name: Install dependencies
+        run: |
+          pipenv install --dev
+      - name: Build docs
+        run: |
+          cd docs
+          pipenv run make html
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: '${{ secrets.GITHUB_TOKEN }}'
+          publish_dir: docs/_build/html