Adding a handbook page to provide guidance on change management requirements for compliance

Why is this change being made?

This change is being made so that we have a dedicated handbook page that provides guidance on all requirements that would need to be met from a change management perspective to support various audits that will be performed over GitLab. The goal is to provide insight into specific requirements needed so that we can effectively evaluate any gaps in the current change management procedures at GitLab.

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