Pre-program task for CEO Shadow to review CEO page

Why is this change being made?

This change adds a section to the Pre-program tasks on the CEO Shadow handbook page. It recommends that new shadows takes time to review the CEO handbook before starting.

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

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