docs(react-native): add iOS deep linking prerequisite steps (URL Types & Associated Domains)

[coderabbitai]

Summary

The React Native SDK deep linking documentation for iOS (in src/content/docs/developer-tools/sdks/native/react-native-sdk.mdx) shows AppDelegate code for handling custom scheme callbacks (openURL) and universal links (continueUserActivity), but is missing the required registration steps that must be performed before those handlers will be invoked by iOS.

Missing documentation

Add a brief prerequisite section before the AppDelegate snippets covering:

• Custom scheme callback: register your scheme under Info > URL Types (CFBundleURLTypes) in Info.plist.
• Universal links: add the Associated Domains capability with applinks:<your-domain> in your entitlements file, and host a valid apple-app-site-association file on the domain.

Without these registrations, iOS will not invoke the AppDelegate handlers shown in the documentation, making the setup instructions incomplete.

References

• Raised during review of PR docs(react-native): update deep link setup instructions #668: docs(react-native): update deep link setup instructions #668
• Review comment: docs(react-native): update deep link setup instructions #668 (comment)

/cc @victoreronmosele