[Docs] Broken Link in contributing.md - Newcomers Welcome Guide

[ankushbhardwaj408]

Current State:
There is a broken link in the contributing.md file related to the "Newcomers Welcome Guide."

Desired State:
The link should be directed to the newcomers page on Layer5.

Contributor Resources

• See the Contributing to getnighthawk.dev Website
• See the Project Site section of GetNighthawk project doc
• 🎨 Wireframes and designs for Nighthawk Site in Figma
• Meshery UI Nighthawk (Performance) in Figma
• 🙋🏾🙋🏼 Questions: Layer5 Discussion Forum and Layer5 Community Slack

[welcome]

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