Removing the outdated and broken link " More training for rocking your profile on LinkedIn" in the HB

Why is this change being made?

"View the slides" under More training for rocking your profile on LinkedIn is broken and leads to an error. Since this page is linked to Onboarding Issue, a few new hires pointed out that they cannot view the slides. It's probably good idea to remove this link on the handbook page or update it with the new slides if available.

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Author Checklist

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• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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