Improve Defend handbook page

Why is this change being made?

Adding additional labels & improving organization of existing content to make working with the Defend team easier.

Does this MR meet the acceptance criteria?

Heck yeah it does!

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