Add multi-view troubleshooting guide for sentry dart

[martinhaintz]

DESCRIBE YOUR PR

Multi-view for web was introduced in Flutter 3.24. As the current sentry dart package is not 100% compatible with this feature I added a guide, how to use sentry with multi-view in Flutter web.

Flutter 3.24 Flutter Docs for multi-view

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PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• [x] Checked Vercel preview for correctness, including links
• [ ] PR was reviewed and approved by any necessary SMEs (subject matter experts)
• [ ] PR was reviewed and approved by a member of the Sentry docs team