Fix example markdown headings #1

	name: Markdown

	on:
	pull_request:
	paths:
	- "*/.md"
	- ".markdownlint.json"
	- ".github/workflows/markdown.yml"
	push:
	branches:
	- main
	paths:
	- "*/.md"
	- ".markdownlint.json"
	- ".github/workflows/markdown.yml"

	permissions:
	contents: read

	jobs:
	markdown:
	name: Validate Markdown
	runs-on: ubuntu-latest

	steps:
	- name: Check out repository
	uses: actions/checkout@v4

	- name: Run markdownlint
	run: npx markdownlint-cli2@latest "*/.md"

	- name: Check code fences
	shell: bash
	run: \|
	set -euo pipefail
	failed=0
	while IFS= read -r file; do
	count=$(grep -c '^```' "$file" \|\| true)
	if [ $((count % 2)) -ne 0 ]; then
	echo "::error file=$file::Odd number of Markdown code fences"
	failed=1
	fi
	done < <(find . -name ".md" -not -path "./.git/")
	exit "$failed"

	- name: Check Mermaid compatibility patterns
	shell: bash
	run: \|
	set -euo pipefail
	failed=0
	while IFS= read -r file; do
	if awk '/^```mermaid/{in_block=1} /^```$/{if(in_block){in_block=0}} in_block && /classDef\|<br\/>\|-- ".*" -->\|—/' "$file" \| grep -q .; then
	echo "::error file=$file::Mermaid block contains a pattern rejected by this template"
	failed=1
	fi
	done < <(find . -name ".md" -not -path "./.git/")
	exit "$failed"

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