Docs: clarify setup, workflow, and contribution guidance in README

[pranjal2004838]

Summary

This PR improves the README to make the YouTube caption processing pipeline more approachable for new users and contributors.

The changes focus on clarifying the project’s purpose, simplifying the workflow explanation, and making setup assumptions more explicit, without modifying any code or research logic.

What changed

• Added a high-level overview explaining what the pipeline does and who it is for
• Clarified the role of key dependencies (UDPipe, punctuation restoration, SoMaJo)
• Simplified and structured the workflow description for easier onboarding
• Added contributor guidance to encourage small, documentation-focused first contributions
• Minor formatting improvements for readability

Why this change

The original README is accurate but assumes familiarity with the research environment and tooling. These documentation updates aim to reduce onboarding friction for:

• New contributors
• Students and researchers exploring the pipeline
• First-time open-source contributors

Scope

• Documentation-only changes
• No modifications to scripts, pipeline behavior, or outputs

Please let me know if you’d prefer any adjustments to tone or structure.