[DOCS] Add documentation for Frontend

[BucketRaphi]

What Documentation is Affected?

• README.md
• CONTRIBUTING.md
• Setup Instructions
• API Documentation
• Overlay Configuration
• Deployment Guide
• Code Comments
• Other: \docs\frontend.md

Problem

So far there's no existing documentation file in \docs\ for the Frontend

Context

• Skill level: Advanced
• Related component: Frontend

[Hazeolation]

Unit Test docs for FE also needed