Use markdown format for docs #1162

	name: ruby-core

	on:
	pull_request:

	push:
	branches:
	- master

	concurrency:
	group: ci-${{ github.ref }}-${{ github.workflow }}

	permissions: # added using https://github.com/step-security/secure-workflows
	contents: read

	jobs:
	ruby_core:
	name: IRB under a ruby-core setup
	runs-on: ubuntu-20.04
	strategy:
	fail-fast: false
	timeout-minutes: 30
	steps:
	- name: Set up latest ruby head
	uses: ruby/setup-ruby@250fcd6a742febb1123a77a841497ccaa8b9e939 # v1.152.0
	with:
	ruby-version: head
	bundler: none
	- name: Save latest buildable revision to environment
	run: echo "REF=$(ruby -v \| cut -d')' -f1 \| cut -d' ' -f5)" >> $GITHUB_ENV
	- uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v3.1.0
	with:
	repository: ruby/ruby
	path: ruby/ruby
	fetch-depth: 10
	- name: Checkout the latest buildable revision
	run: git switch -c ${{ env.REF }}
	working-directory: ruby/ruby
	- name: Install libraries
	run: \|
	set -x
	sudo apt-get update -q \|\| :
	sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev bison autoconf ruby
	- name: Build Ruby
	run: \|
	autoconf
	./configure -C --disable-install-doc
	make -j2
	working-directory: ruby/ruby
	- uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v3.1.0
	with:
	path: ruby/irb
	- name: Sync tools
	run: \|
	ruby tool/sync_default_gems.rb irb
	working-directory: ruby/ruby
	- name: Test IRB
	run: make -j2 -s test-all TESTS="irb --no-retry"
	working-directory: ruby/ruby

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