Create comprehensive README for repository

[chrisgroks]

Overview

Create a comprehensive README.md for the splunk-banking repository.

Requirements

• Project overview and purpose (demonstrating messy Splunk for AI-assisted refactoring)
• Quick start instructions
• Repository structure (banking-demo submodule + documentation folder)
• Demo instructions
• Testing guide
• Contributing guidelines

Key Info

• Link to banking-demo: https://github.com/chrisgroks/splunk-banking-demo
• Reference documentation/COMPLETE_GUIDE.md
• Login: john_doe / password123
• Current state: Intentionally messy Splunk implementation
• Roadmap: Clean up and migrate to OpenTelemetry

Acceptance Criteria

• Clear project description
• Working quick start instructions
• Links to detailed documentation
• Professional tone