Update README for latest installation instructions with automated publishing

[Copilot]

Updated the README to reflect the current automated npm publishing setup and ensure all installation instructions are accurate and up-to-date.

Changes Made

📦 Installation Section

• Added separate sections for stable and beta releases
• Documented the automated GitHub Actions publishing system
• Added note explaining when stable vs beta releases are published

🛠️ CLI Examples

• Updated command examples with helpful comments
• Added the region command to the examples (useful for seeing available regions)
• Verified all example commands work correctly
• Improved the ordering of commands for better user flow

🔧 Development Instructions

• Updated development setup to include correct directory navigation
• Added missing cd tailportal step after cloning
• Specified that commands should be run from packages/tailportal directory
• Updated example commands to match current CLI implementation

✅ Verification

• All existing e2e tests continue to pass
• Created comprehensive tests to verify README accuracy
• Confirmed all documented commands work as expected
• Validated that example regions (like ewr) are valid

The README now accurately reflects:

• Both stable (npm install -g tailportal) and beta (npm install -g tailportal@beta) installation options
• The automated publishing workflow via GitHub Actions
• Current CLI commands and their proper usage
• Correct development setup procedures

Fixes #10.

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.