(feat): Updates to root README

[courtzc]

📥 Pull Request

🔗 Related Issue(s)

Close #278

❓ What are you trying to address

Make CAIRA's offerings clearer and more obvious, including:

• Links to other CAIRA assets
• Clear information about the RAs in root readme
• More prominent introduction of the CAIRA Assistant

✨ Description of new changes

• Adds the CAIRA assets table to the root README of this repository. Includes the list of assets, their purpose, what they offer, and a link to the repository.
• Copies the reference architecture table into the root README
• Moves the caira assistant up in the root README to before the manual steps.

☑️ Checklist

• 🔍 I have performed a self-review of my own code.
• 📝 I have commented my code, particularly in hard-to-understand areas.
• 🧹 I have run the linter and fixed any issues (if applicable).
• 📄 I have updated the documentation to reflect my changes (if necessary).

[Copilot]

Pull Request Overview

This PR enhances the discoverability and clarity of CAIRA's offerings by reorganizing and expanding the root README. The changes make it easier for users to understand the CAIRA ecosystem and get started with deployments through better documentation structure and more prominent assistant guidance.

• Added a comprehensive CAIRA Assets table to showcase the full suite of acceleration offerings
• Reorganized the Getting Started section to prioritize the CAIRA Assistant chat mode for guided deployment
• Added reference architecture links in the reference_architectures/README.md for better navigation

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
README.md	Restructured to add CAIRA assets overview table, moved CAIRA Assistant to Quick Start section, and updated Getting Started instructions with assistant references
reference_architectures/README.md	Added navigation links to specific reference architecture directories for all four configurations

[PabloZaiden]

@courtzc, can you take a look at the open conversations so we can resolve them and merge the PR?