docs: Improve `Validation` docs #4881

	# When a Pull Request is opened that modifies
	# the User Guide source, build the User Guide
	# with Sphinx and let the contributor know of
	# any errors.
	name: Test User Guide

	on:
	pull_request:
	paths:
	- 'user_guide_src/**'
	- '.github/workflows/test-userguide.yml'

	concurrency:
	group: ${{ github.workflow }}-${{ github.head_ref \|\| github.run_id }}
	cancel-in-progress: true

	permissions:
	contents: read

	jobs:
	syntax_check:
	name: Check User Guide syntax
	runs-on: ubuntu-22.04

	steps:
	- name: Checkout
	uses: actions/checkout@v4

	- name: Setup Python
	uses: actions/setup-python@v5
	with:
	python-version: '3.12'

	- name: Install Sphinx
	run: \|
	python -m pip install --upgrade pip
	pip install -r user_guide_src/requirements.txt

	- name: Detect usage of tabs in RST files
	run: php utils/check_tabs_in_rst.php

	- name: Build Docs with Sphinx
	run: make html SPHINXOPTS="-W --keep-going -w /tmp/sphinx-log"
	working-directory: user_guide_src

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