Adding an example pull request tutorial #3

	name: AddBinderBadge
	# https://github.com/jupyterhub/repo2docker-action#cache-builds-on-mybinderorg-and-provide-a-link
	on:
	pull_request:
	types: [opened, reopened]
	paths:
	- 'book/tutorials/**'
	- '.github/workflows/binder-badge.yml'
	- 'conda/**'
	jobs:
	add-badge:
	runs-on: ubuntu-20.04
	steps:
	- name: Checkout PR
	uses: actions/checkout@v2

	- name: cache binder build on mybinder.org
	uses: jupyterhub/repo2docker-action@master
	with:
	NO_PUSH: true
	MYBINDERORG_TAG: ${{ github.event.pull_request.head.ref }}

	- name: Comment on PR with Binder link
	uses: actions/github-script@v3
	env:
	BRANCH_NAME: ${{ github.event.pull_request.head.ref }}
	CONTENT_REPO: ${{github.event.pull_request.head.repo.full_name}}
	with:
	github-token: ${{secrets.GITHUB_TOKEN}}
	script: \|
	var BRANCH_NAME = process.env.BRANCH_NAME;
	var CONTENT_REPO = process.env.CONTENT_REPO;
	github.issues.createComment({
	issue_number: context.issue.number,
	owner: context.repo.owner,
	repo: context.repo.repo,
	body: `[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${context.repo.owner}/${context.repo.repo}/${BRANCH_NAME}) :point_left: Launch a binder notebook on this branch`
	})

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