add GitHub Actions workflow to build Antora documentation. #2

	# Copyright 2021 The Khronos Group, Inc.
	# SPDX-License-Identifier: Apache-2.0

	# Github workflow file for Antora documentation build

	name: Antora Build

	# Controls when the action will run.
	on:
	pull_request:
	types: [ opened, synchronize, reopened ]
	# Triggers the workflow on push or manual dispatch
	push:
	workflow_dispatch:
	concurrency:
	group: ${{ github.workflow }}-${{ github.head_ref \|\| github.ref }}
	cancel-in-progress: true

	jobs:
	antora-build:
	runs-on: ubuntu-latest

	steps:
	# Checks-out your repository under $GITHUB_WORKSPACE, so your job can
	# access it
	- uses: actions/checkout@v3

	# Set up Node.js environment
	- name: Setup Node.js
	uses: actions/setup-node@v3
	with:
	node-version: '16'

	# Install Antora CLI and site generator
	- name: Install Antora
	run: npm i -g @antora/cli@3.1 @antora/site-generator@3.1

	# Setup Antora directory structure
	- name: Setup Antora directory structure
	run: \|
	cd antora
	make setup

	# Create a simple Antora playbook
	- name: Create Antora playbook
	run: \|
	echo "site:
	title: Vulkan Guide
	url: https://github.com/KhronosGroup/Vulkan-Guide
	start_page: guide::index.adoc
	content:
	sources:
	- url: .
	start_path: antora
	ui:
	bundle:
	url: https://gitlab.com/antora/antora-ui-default/-/jobs/artifacts/HEAD/raw/build/ui-bundle.zip?job=bundle-stable
	snapshot: true" > antora-playbook.yml

	# Run Antora build
	- name: Build Antora site
	run: antora --stacktrace antora-playbook.yml

	# Archive the build artifacts
	- name: Archive Antora build
	uses: actions/upload-artifact@v4
	with:
	name: antora-site
	path: build/site

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