Fix README check snippet

[alextu]

Forgot to update the README with the previous PR changing the way to enable quality checks.

• [x] Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• [x] Ensure that the pull request title represents the desired changelog entry
• [x] Please describe what you did
• [x] Link to relevant pull requests, esp. upstream and downstream changes

[sghill]

Thank you @alextu!