fix typographical mistakes in comments #291

	# Based on https://docs.platformio.org/en/latest/integration/ci/github-actions.html
	name: PlatformIO CI

	on: [push, pull_request]

	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Cache pip
	uses: actions/cache@v2
	with:
	path: ~/.cache/pip
	key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
	restore-keys: \|
	${{ runner.os }}-pip-
	- name: Cache PlatformIO
	uses: actions/cache@v2
	with:
	path: ~/.platformio
	key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
	- name: Set up Python
	uses: actions/setup-python@v2
	- name: Install PlatformIO
	run: \|
	python -m pip install --upgrade pip
	pip install --upgrade platformio

	- name: Run PlatformIO
	run: pio run -e STM32F1 -e STM32F1-USB -e STM32F1-XCVR -e STM32F1-USB-96MHz -e STM32F1-USB-128MHz

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