docs: add GitHub Packages authentication setup instructions

Add comprehensive setup instructions for GitHub Packages authentication
required to install React on Rails Pro dependencies.

Changes:
- Add Prerequisites section with step-by-step token creation
- Document npm configuration for @shakacode-tools packages
- Document Bundler configuration for rubygems.pkg.github.com
- Add note about installation failure without authentication
- Clarify that each developer needs their own GitHub token

This addresses best practices for token management in demo repositories
where each developer should use their own credentials rather than
sharing tokens.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ihabadham

README.md

@@ -78,12 +78,29 @@ This demo includes comprehensive documentation for both developers and AI coding
 
 ## 🚀 Quick Start
 
+### Prerequisites: GitHub Packages Authentication
+
+This demo uses **React on Rails Pro** from GitHub Packages. While RORP will be open source soon, it currently requires authentication with your Pro subscription token.
+
+1. **Configure npm for GitHub Packages:**
+   ```bash
+   npm config set @shakacode-tools:registry https://npm.pkg.github.com
+   npm config set //npm.pkg.github.com/:_authToken YOUR_PRO_TOKEN
+   ```
+
+2. **Configure Bundler for GitHub Packages:**
+   ```bash
+   bundle config rubygems.pkg.github.com YOUR_PRO_TOKEN
+   ```
+
+### Installation
+
 ```bash
 # Clone the demo repository
 git clone https://github.com/shakacode/react_on_rails-demo-v15-ssr-auto-registration-bundle-splitting.git
 cd react_on_rails-demo-v15-ssr-auto-registration-bundle-splitting
 
-# Install dependencies
+# Install dependencies (after configuring GitHub Packages above)
 bundle install && npm install
 
 # Start development server
@@ -93,6 +110,8 @@ bundle install && npm install
 open http://localhost:3000
 ```
 
+**Note:** Without GitHub Packages authentication, `bundle install` and `npm install` will fail when trying to download `react_on_rails_pro` and `@shakacode-tools/react-on-rails-pro-node-renderer`.
+
 ### 🌐 Demo Components
 
 - **[HelloWorld](http://localhost:3000)** - Lightweight component (12.5KB bundle)