Add Project, Repo & Architecture Documentation

[luffyofproduct]

Summary:

This PR adds documentation for the dbt project, repository & overall architecture.

Details:

• Architecture:
  • Created a Data Architecture Handbook to serve as a living reference guide for the end-to-end architecture (strategies, tools, etc.)
• Repository:
  • Updated the Readme to serve as a "cover page" for the repository that explains the underlying project & provides quick links.
• Project:
  • Added example model/macro documentation for existing objects and a Style Guide for long term consistency.
  • Added a requirements.txt

Links:

• dbt Docs Commands