docs: improve README structure and onboarding experience

[shikha123-ops]

Description

This PR improves the README documentation by enhancing its structure, navigation, and overall readability for both users and contributors.

Changes Made

• Added a comprehensive Table of Contents for easier navigation
• Introduced a Quick Start section to simplify project onboarding
• Added a Project Status section
• Added a Tech Stack overview highlighting the technologies used in ARVIO
• Added a Contributing section with contribution workflow and submission guidelines
• Improved screenshot presentation and documentation organization
• Standardized formatting and section hierarchy for better readability

Benefits

• Improves documentation quality and maintainability
• Makes onboarding easier for new contributors
• Helps users quickly find important project information
• Enhances overall navigation and user experience
• Provides a more professional and structured project presentation

Type of Change

• Documentation update
• Bug fix
• New feature
• Breaking change

Notes

This PR only modifies documentation and does not introduce any application or functionality changes.