Add guidance on Architecture Review Board (ARB) process

We should add guidance e.g., in this repository's Wiki, Notion, etc., on how project deliverables e.g., applications, must follow the Architecture Review Board (ARB) process for deployment. This includes submitting various documentation e.g., High Level Design (HLD), Data Protection Impact Assessment (DPIA), System Level Security Policy (SLSP), etc., raising IT tickets e.g., New Project Request, and having this request raised in various boards e.g., Non-Standard Demand Board, Change Advisory Board (CAB), etc.