Add dbt guide to data team handbook

Why is this change being made?

There have been several requests to have a more defined space for dbt-specific guidance and information. This is the MVC for that change pulling in documentation from the SQL Style Guide and the main Data Team page.

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