Remove source generators overview

[BillWagner]

The cookbook, from the roslyn SDK is a better choice.

Fixes #42768

Because the content was removed, the following issues have also been addressed:

Closes #24796
Closes #27042
Closes #30659
Closes #30728
Closes #30925
Closes #32740
Closes #33757
Closes #33936
Closes #35939
Closes #37487
Closes #39990
Closes #40058
Closes #42031

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docs/architecture/maui/mvvm-community-toolkit-features.md	docs/architecture/maui/mvvm-community-toolkit-features
docs/core/docker/build-container.md	docs/core/docker/build-container
docs/core/extensions/configuration-generator.md	docs/core/extensions/configuration-generator
docs/core/testing/unit-testing-platform-architecture-extensions.md	docs/core/testing/unit-testing-platform-architecture-extensions
docs/core/whats-new/dotnet-6.md	docs/core/whats-new/dotnet-6
docs/csharp/programming-guide/classes-and-structs/partial-classes-and-methods.md	docs/csharp/programming-guide/classes-and-structs/partial-classes-and-methods
docs/csharp/roslyn-sdk/index.md	docs/csharp/roslyn-sdk/index
docs/standard/base-types/regular-expression-source-generators.md	docs/standard/base-types/regular-expression-source-generators
docs/standard/native-interop/pinvoke-source-generation.md	docs/standard/native-interop/pinvoke-source-generation
docs/standard/serialization/system-text-json/overview.md	docs/standard/serialization/system-text-json/overview
docs/standard/serialization/system-text-json/reflection-vs-source-generation.md	docs/standard/serialization/system-text-json/reflection-vs-source-generation