Expand README with motivation, architecture summary, and feature links

[jtdub]

Description

The current README is 76 lines — functional but minimal. It doesn't explain why hierarchical configuration analysis matters, doesn't show output from the Quick Start, and doesn't link to key features like tagging, reporting, or config views.

For a v3.4.1 production library, the README is the most-viewed documentation and should make a stronger first impression.

Proposed Improvements

1. Add a "Why hier_config?" section — Briefly explain the problem (config drift, manual remediation, multi-platform complexity) and how the hierarchical tree approach solves it
2. Show output in Quick Start — The current example stops at print(workflow.remediation_config) without showing what gets printed
3. Add a feature highlights section linking to:
   • Rollback generation
   • future() for predicting device state
   • Tag-based selective remediation
   • Multi-device reporting
   • Config views
4. Add a brief architecture blurb — One paragraph + a simple diagram showing the data flow
5. Link to key docs pages — drivers, custom workflows, reporting