Clarify last cascading delete example

First of all, great article and great functionality!
My question concerns the last example. Is this really a case of cascading deletion?

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#### Document Details

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* ID: 0f0fb981-4dec-7ff7-817b-6606f620b875
* Version Independent ID: c7517e7d-f011-a24c-53da-913771913998
* Content: [Saving Related Data - EF Core](https://docs.microsoft.com/en-us/ef/core/saving/related-data#feedback)
* Content Source: [entity-framework/core/saving/related-data.md](https://github.com/aspnet/EntityFramework.Docs/blob/master/entity-framework/core/saving/related-data.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @rowanmiller
* Microsoft Alias: **avickers**