Fix conflicting System.Exception recommendation in Visual Basic documentation

[Copilot]

The Visual Basic documentation for the Throw statement was showing an example that conflicts with established .NET best practices. The example demonstrated throwing System.Exception directly:

Throw New System.Exception("An exception has occurred.")

However, the C# documentation correctly advises against this practice, stating: "Don't throw System.Exception, System.SystemException, System.NullReferenceException, or System.IndexOutOfRangeException intentionally from your own source code."

This created inconsistent guidance across the .NET documentation where Visual Basic developers might follow the example and violate best practices.

The fix updates the Visual Basic example to use InvalidOperationException instead:

Throw New InvalidOperationException("The operation is not valid for the current state.")

This change:

• Aligns with Microsoft's official exception throwing guidelines
• Resolves the conflict between VB and C# documentation
• Uses InvalidOperationException, which is explicitly recommended in the best practices documentation
• Maintains the same educational value for demonstrating the Throw statement syntax

Fixes #35262.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[BillWagner]

This is ready for final review.