7.5: Create README Documentation

[justin808]

Overview

Document the demo application.

Parent Epic: #70
Priority: P2

Prerequisites

• All previous issues complete

Next Issues (after this is complete)

• None - this is the final issue

Acceptance Criteria

• README.md with project overview
• Setup instructions (prerequisites, installation, running locally)
• Architecture explanation (RSC patterns used)
• File structure documentation
• Key RSC patterns documented with code examples
• Comparison with Next.js version (what's similar, what's different)
• Links to React on Rails Pro documentation
• Contributing guidelines (if accepting contributions)

Implementation Notes

README sections to include:

1. Overview - What this demo shows
2. Live Demo - Link to deployed version
3. Quick Start - Get running in 5 minutes
4. Architecture - How RSC works with Rails
5. Key Patterns - Server vs Client components
6. Comparison - Next.js vs React on Rails Pro
7. Learn More - Links to RoR Pro docs

Reference the original Vercel demo:
https://github.com/vercel/next-react-server-components