docs: Improve README clarity and usability

[surajranaofficial]

Summary

This PR improves the README documentation to make it more user-friendly and easier to navigate for new users.

Changes Made

Grammar and Punctuation

• Fixed grammar error: organization of enterprise → organization or enterprise
• Added missing period after model selection description
• Replaced double dash with em dash for proper typography

New Sections Added

⚡ Quick Start

• Added a concise 3-step quick start section at the beginning
• Helps users get started immediately without reading the entire README

Common Commands

• Listed frequently used slash commands with descriptions
• Makes it easier for users to discover available commands

Usage Tips

• Added practical tips for using the CLI effectively
• Helps users understand best practices

Structured Feedback Section

• Reorganized feedback information into clear subsections
• Added "How to Provide Feedback" with bullet points
• Added "Getting Help" section with resource links

Impact

• Better onboarding: Quick Start section reduces time to first use
• Improved discoverability: Common Commands section helps users find features
• Clearer guidance: Usage Tips provide actionable advice
• Better organization: Structured sections make information easier to find

Type of Change

• Documentation improvement
• Non-breaking change
• Improves user experience

Testing

• Markdown formatting verified
• All links tested and working
• Content accuracy verified against current CLI behavior