add sphinx docu build

Author: brentru

.github/workflows/build.yml

@@ -18,10 +18,16 @@ jobs:
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
     - name: Install library
       run: python3 setup.py install
+    - name: Install sphinx
+      run: pip3 install pylint Sphinx sphinx-rtd-theme
     - name: Run all unittests
       env: 
         SECRET_IO_KEY: ${{ secrets.CI_IO_KEY }}
         SECRET_IO_USER: ${{ secrets.CI_IO_USERNAME }}
       run: |
         cd tests/
-        ADAFRUIT_IO_KEY=$SECRET_IO_KEY ADAFRUIT_IO_USERNAME=$SECRET_IO_USER python -m unittest discover
+        ADAFRUIT_IO_KEY="$SECRET_IO_KEY" ADAFRUIT_IO_USERNAME="$SECRET_IO_USER" python -m unittest discover
+        cd ..
+    - name: Generate documentation
+      run: |
+        cd docs && sphinx-build -E -W -b html . _build/html && cd ..