rtos: io_drivers: add loopback mode description #274

	---
	# Tools that can save round-trips to github and a lot of time:
	#
	# yamllint -f parsable pull_request.yml
	# pip3 install ruamel.yaml.cmd
	# yaml merge-expand pull_request.yml exp.yml &&
	# diff -w -u pull_request.yml exp.yml
	#
	# github.com also has a powerful web editor that can be used without
	# committing.
	name: woke PR reviewdog checker

	# yamllint disable-line rule:truthy
	on:
	pull_request:
	branches:
	- master

	jobs:
	woke_pr:
	name: woke check for patch
	runs-on: ubuntu-20.04
	steps:
	- uses: actions/checkout@v3
	- uses: get-woke/woke-action-reviewdog@v0
	with:
	github-token: ${{ secrets.GITHUB_TOKEN }}
	# Change reviewdog reporter if you need [github-pr-check,github-check,github-pr-review].
	reporter: github-pr-review
	# Change reporter level if you need.
	# GitHub Status Check won't become failure with warning.
	level: warning
	# Enable this to fail the check when violations are found
	fail-on-error: true
	woke-args: -c ./rules-woke.yaml

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