Diagram is missing Event Notifications

[ocofaigh]

Diagram is missing Event Notifications: https://github.com/terraform-ibm-modules/dev-rag/blob/main/reference-architecture/rag-stack.svg

While updating, review the whole content of the diagram, as it was suggest that we may want to re-order some of the content

[ajainghub]

@ocofaigh Please update these two diagrams in content:

1. Reference architecture (added wx Orchestrate to the architecture)
2. Solution components (added wx Orchestrate, Event Notifications, and reordered the stack)

[ocofaigh]

Updated diagrams coming in #42