fix Sphinx warnings #48

	name: release
	on:
	push:
	branches:
	- master

	jobs:
	release:
	name: Build documentation
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v2.0.0
	- name: Set up Python
	uses: actions/setup-python@v2
	with:
	python-version: '3.9'
	- name: Cache dependencies
	uses: actions/cache@v2.1.3
	with:
	path: ~/.cache/pip
	key: ${{ runner.os }}-pip-py3.9-${{ hashFiles('**/requirements.txt') }}
	restore-keys: \|
	${{ runner.os }}-pip-
	- name: Install dependencies
	run: \|
	sudo apt-get update
	sudo apt-get install graphviz
	python -m pip install --upgrade pip
	pip install -r requirements.txt
	- name: Build sphinx documentation
	run: \|
	cd docs
	make html
	cd _build/html
	touch .nojekyll
	- name: Push to gh-pages
	env:
	PERSONAL_TOKEN: ${{ secrets.PAGES_TOKEN }}
	PUBLISH_BRANCH: gh-pages
	PUBLISH_DIR: docs/_build/html
	SCRIPT_MODE: true
	INPUT_EMPTYCOMMITS: false
	run: \|
	wget https://raw.githubusercontent.com/peaceiris/actions-gh-pages/v2.9.0/entrypoint.sh
	bash ./entrypoint.sh

Provide feedback