Update links to https://docs.ultralytics.com

copilot:all

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

Upgraded automation for community interaction and issue management.

Triggered greeting workflows only when PRs and issues are opened.
Simplified PR greeting with a link to the Contributing Guide.
Issue messages now direct users to install the Ultralytics package and highlight YOLOv8 environment setup.
Updated Continuous Integration (CI) badge and references to YOLOv8.
Stale workflow updated to use actions/stale@v8.
Enhanced stale messages for issues and PRs with additional resources and community links.
Adjusted stale and closing timelines for issues and PRs.

💻 Enhances the initial response to contributors for better guidance and direction.
🛠 Provides clearer installation and set-up instructions, promoting a smoother start for users.
🔄 Keeps the project's issues and PRs more active and relevant by closing off stale ones more effectively.
🌐 Expands the scope of resources available to contributors, fostering a more inclusive and informed community.