chore(docs): add external link for a Modular SwiftUI Multi-platform example

[hgq287]

Summary

Added a link to a SwiftUI Multi-platform (iOS & macOS) example in Docs/Examples.md.

Why this is helpful

Modern apps often need to share code between iOS and macOS. This example shows:

• Modular Setup: App, Shared, and Core layers.
• SwiftUI: Shared views and app lifecycle.
• Dependencies: How to use Alamofire and GRDB with XcodeGen.
• Best Practices: Using .xcconfig and SUPPORTED_PLATFORMS.

Checklist

• Link works correctly.
• Project generates successfully with XcodeGen.

[hgq287]

Hi @yonaskolb , I noticed the Ci failed at the Build fixtures step with xcodebuild: error: Found no destinations for the scheme 'App_iOS Test'. It seems like an environment issue with the CI's Xcode destinations rather than my documentation changes. Could you please take a look or trigger a re-run? Thanks!