docs: updates license text header in the contributing guide #59

	name: Validate proposals with trestle
	on:
	pull_request:
	branches:
	- main
	jobs:
	validate:
	runs-on: ubuntu-latest
	steps:
	- name: Don't mess with line endings
	run: \|
	git config --global core.autocrlf false

	- uses: actions/checkout@v4

	- name: Set up Python
	uses: actions/setup-python@v5
	with:
	python-version: '3.11'
	cache: 'pip'

	- name: Install trestle
	run: pip install -r requirements.txt

	- name: Run trestle validate
	run: trestle author docs validate -tn proposals -hv

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