Add more guidance for scheduling C1/C2 change issues during shift changes for on-call

Why is this change being made?

When scheduling a change issue, we should consider that starting a change issue when a shift change is occurring can add extra complication and stress to the incoming on-call individual(s). Let's try to avoid this when possible by considering these shift changes when scheduling changes.

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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  • The when to get approval handbook section explains the workflow in more detail
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  • Team: For changes that affect your direct team, share in your group Slack channel
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Commits

• Add more guidance for scheduling C1/C2 change issues

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