Add steps for using Compaas for approvers and slate owners.

@brittanyr Please make any edits as you see fit. Screenshots to follow.

Why is this change being made?

This adds steps for managers and slate approvers to follow for using our annual compensation review platform, Compaas.

Does this MR meet the acceptance criteria?

Conformity

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