Update Sick Time reporting guidelines

Why is this change being made?

GitLab's Sick Time policy did not clearly explain who team members should report their time away to and when. Instead, it implied that entering the time away into PTO by Deel was sufficient and met the requirement of reporting sick time to the employer. Because that does not meet the requirement, I've updated the steps to better explain the cadence of who to contact, when, and when to enter the time away into PTO by Deel.

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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