Issue #142 initial GitHub workflow for doc build+publish

.github/workflows/docs2ghpages.yml

@@ -0,0 +1,42 @@
+name: Build docs and push to GitHub Pages
+
+on: push
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: 3.12
+
+    - name: Install dependencies (including Sphinx)
+      run: python -m pip install -r docs/requirements.txt
+
+    - name: Sphinx build
+      # Build HTML documentation from sources under `docs` to `build` folder.
+      run: python -m sphinx -b html docs build
+
+    - name: Commit documentation in gh-pages branch
+      # Store documentation in a temporary one-commit git repo.
+      run: |
+        cd build
+        git init -b gh-pages
+        touch .nojekyll
+        git config --local user.name "GitHub Actions Bot"
+        git config --local user.email "actions@github.com"
+        git add .
+        git commit -m "Update documentation"
+
+    - name: Push gh-pages branch
+      # Push from the temporary repo to the `gh-pages` branch of your repo.
+      # Warning: this will overwrite any existing content and history
+      # of the `gh-pages` branch.
+      run: |
+        cd build
+        git push --force "https://${GITHUB_ACTOR}:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}" gh-pages
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}