Add link to Secure Team specific coding style guide

Why is this change being made?

Following this discussion regarding using goimports instead of gofmt in the company-wide Go style guide, this MR adds a coding style guide section to the Secure Section of the handbook to allow the Secure Team to override certain aspects of the general style guide.

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