[Docs] Add a link to the plugin's design spec to the Readme

[ritzorama]

Current State

Desired State

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Contributor Guides and Handbook

• 📚 Instructions for contributing to documentation
  • Meshery documentation site and source
• 🛠 Meshery Build & Release Strategy
• 🎨 Wireframes and designs for Meshery UI in Figma (open invite)
• 🙋🏾🙋🏼 Questions: Discussion Forum and Community Slack

[welcome]

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[stale]

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