Rework README and move dev instructions to contributing #1446

	# This is a basic workflow to check for broken links with GitHub Actions

	name: Link Checker

	on:
	push:
	branches:
	- main
	- "renovate/**"
	pull_request:

	jobs:
	link-checker:
	timeout-minutes: 2
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4

	- name: Link Checker
	id: lychee
	uses: lycheeverse/lychee-action@7cd0af4c74a61395d455af97419279d86aafaede # v2.0.2
	with:
	# Exclude the image.sc forum (which works) but returns 403 from
	# github runners and exclude relative links to other pages. Ignore
	# gnu.org and fsf.org because they're often down but are still the right
	# websites to link to!
	#
	# Ignore the whole of the project slug README since the links are
	# necessarily not real links - i.e. demos and to be filled by
	# cookiecutter values.
	args: "--verbose
	--exclude https://forum.image.sc/
	--exclude http://www.gnu.org
	--exclude http://fsf.org
	--exclude docs/pages
	--exclude-path '{{cookiecutter.project_slug}}/README.md'
	--exclude-path 'tests/data'
	-- ."
	fail: true
	jobSummary: true
	env:
	GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

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