minor(docs): Add docs for `regen.sh` (#13321) #456

	on:
	push:
	branches:
	- main
	paths:
	- .asf.yaml
	- .github/workflows/docs.yaml
	- docs/**

	name: Deploy DataFusion site

	jobs:
	build-docs:
	name: Build docs
	runs-on: ubuntu-latest
	steps:
	- name: Checkout docs sources
	uses: actions/checkout@v4

	- name: Checkout asf-site branch
	uses: actions/checkout@v4
	with:
	ref: asf-site
	path: asf-site

	- name: Setup Python
	uses: actions/setup-python@v5
	with:
	python-version: "3.10"

	- name: Install dependencies
	run: \|
	set -x
	python3 -m venv venv
	source venv/bin/activate
	pip install -r docs/requirements.txt

	- name: Build docs
	run: \|
	set -x
	source venv/bin/activate
	cd docs
	./build.sh

	- name: Copy & push the generated HTML
	run: \|
	set -x
	cd asf-site/
	rsync \
	-a \
	--delete \
	--exclude '/.git/' \
	../docs/build/html/ \
	./
	cp ../.asf.yaml .
	touch .nojekyll
	git status --porcelain
	if [ "$(git status --porcelain)" != "" ]; then
	git config user.name "github-actions[bot]"
	git config user.email "github-actions[bot]@users.noreply.github.com"
	git add --all
	git commit -m 'Publish built docs triggered by ${{ github.sha }}'
	git push \|\| git push --force
	fi

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