Contributor-oriented Architecture Guide

[mpstefan]

As a potential contributor for NGF
I want a contributor-oriented architecture guide that helps me understand the underlying components of NGF
So that I can better understand how to contribute to the project in code.

Acceptance

• A link to the user-oriented architecture guide is present
• The architecture guide explains all major components of NGF that are not present in the user-oriented architecture guide so that a contributor understands how they might contribute code for a feature.
• The user-oriented guide is a prerequisite for the contributor-oriented guide (???)