add diagram showing system overview

[patrickdemers6]

Description

Adding a diagram which shows system architecture.

Type of change

Please select all options that apply to this change:

• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] Documentation update

Checklist:

Confirm you have completed the following steps:

• [ ] My code follows the style of this project.
• [ ] I have performed a self-review of my code.
• [X] I have made corresponding updates to the documentation.
• [ ] I have added/updated unit tests to cover my changes.
• [ ] I have added/updated integration tests to cover my changes.

[ThomasAlxDmy]

Why are we documentating deprecated flow?

[patrickdemers6]

@ThomasAlxDmy this is the required flow at this point. This will be updated once the new flow is available.