Add SG.5.07 to handbook

Why is this change being made?

This change adds the new SG.5.07 (Board of Directors Security Program Content) control to the handbook.

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