Update NotSupportedException for BinaryFormatter (de)serialize

[gewarren]

Contributes to dotnet/docs#34891.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[learn-build-service-prod]

Learn Build status updates of commit 4f2fa97:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Runtime.Serialization.Formatters.Binary/BinaryFormatter.xml	✅Succeeded	View

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[gewarren]

@jeffhandley Could you review this?

[jeffhandley]

Thanks for covering this, @gewarren!