Update ONBOARDING.md

[Jquinny]

Proposed changes

Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request. If it relates to an open issue, be sure to link to that issue. Ensure that you add a label to the PR describing the type of change (if the issue does not have one already for whatever reason).

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [ ] I have read the CONTRIBUTING doc
• [ ] Lint and unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added the necessary documentation (if appropriate)
• [ ] Any changes to main have been merged into my branch

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

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