docs feat: Missing “Start Here: New Contributor Quickstart” Section to README

[samyuktha2004]

Many new contributors land on the repository and may feel overwhelmed or unsure where to begin. While the official documentation is comprehensive, a concise onboarding checklist in the README will make the first steps clearer and more accessible.

Proposal: Add a “Start Here: New Contributor Quickstart” section above the Contributions section in the README, summarizing the key onboarding steps and linking to the official documentation, Code of Conduct, CLA, and community resources.

Value:

• Reduces friction for first-time contributors
• Aligns with open source best practices
• Complements, but does not duplicate, the official contributor guide

[samyuktha2004]

#39962
PR created

[Bhawya-26]

Hi, I would like to work on this issue.