Document how to configure TPT base-linking FKs

See https://github.com/dotnet/efcore/issues/24622#issuecomment-905046687

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#### Document Details

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* ID: a10898c5-abee-1843-cfff-b2707f8a079a
* Version Independent ID: d9399618-488e-20b1-f707-35a191b95cc1
* Content: [Inheritance - EF Core](https://docs.microsoft.com/en-us/ef/core/modeling/inheritance)
* Content Source: [entity-framework/core/modeling/inheritance.md](https://github.com/dotnet/EntityFramework.Docs/blob/main/entity-framework/core/modeling/inheritance.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @AndriySvyryd
* Microsoft Alias: **avickers**