Clarify delegate as built-in reference type in documentation (dotnet#47668)

* Initial plan

* Initial analysis: Understanding delegate type classification issue

Co-authored-by: BillWagner <[email protected]>

* Clarify delegate as built-in type in documentation

Co-authored-by: BillWagner <[email protected]>

* Remove package.json files from tracking

* Remove unrelated .gitignore change for node_modules

Co-authored-by: gewarren <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: BillWagner <[email protected]>
Co-authored-by: gewarren <[email protected]>

Author: 3 people

docs/csharp/language-reference/builtin-types/built-in-types.md

@@ -37,7 +37,7 @@ The following table lists the C# built-in [reference](../keywords/reference-type
 | [`delegate`](reference-types.md#the-delegate-type) |<xref:System.Delegate?displayProperty=nameWithType> |
 | [`dynamic`](reference-types.md#the-dynamic-type)   |<xref:System.Object?displayProperty=nameWithType>   |
 
-In the preceding tables, the C# type keyword from the left column (except [delegate](reference-types.md#the-delegate-type) and [dynamic](reference-types.md#the-dynamic-type)) is an alias for the corresponding .NET type. They're interchangeable. For example, the following declarations declare variables of the same type:
+In the preceding tables, most C# type keywords from the left column are aliases for the corresponding .NET type. They're interchangeable. For example, the following declarations declare variables of the same type:
 
 ```csharp
 int a = 123;
@@ -50,7 +50,7 @@ The `dynamic` type is similar to `object`. The main differences are:
 - You can't use `new dynamic()`.
 - You can't derive a type from the `dynamic` type.
 
-The `delegate` keyword declares a type derived from <xref:System.Delegate?displayProperty=nameWithType>. `System.Delegate` type is an abstract type.
+The `delegate` keyword is a built-in reference type keyword that declares a type derived from <xref:System.Delegate?displayProperty=nameWithType>. Unlike the other built-in type keywords, `delegate` isn't an alias for a specific .NET type. Instead, it declares custom types that derive from the abstract `System.Delegate` type. Similarly, `dynamic` represents runtime binding behavior rather than being a direct alias for a specific .NET type.
 
 The [`void`](void.md) keyword represents the absence of a type. You use it as the return type of a method that doesn't return a value.
 

docs/csharp/language-reference/builtin-types/reference-types.md

@@ -210,7 +210,7 @@ public delegate int AnotherDelegate(MyType m, long num);
 
 In .NET, `System.Action` and `System.Func` types provide generic definitions for many common delegates. You likely don't need to define new custom delegate types. Instead, you can create instantiations of the provided generic types.
 
-A `delegate` is a reference type that can be used to encapsulate a named or an anonymous method. Delegates are similar to function pointers in C++; however, delegates are type-safe and secure. For applications of delegates, see [Delegates](../../programming-guide/delegates/index.md) and [Generic Delegates](../../programming-guide/generics/generic-delegates.md). Delegates are the basis for [Events](../../programming-guide/events/index.md). A delegate can be instantiated by associating it either with a named or anonymous method.
+A `delegate` is a built-in reference type that can be used to encapsulate a named or an anonymous method. Delegates are similar to function pointers in C++; however, delegates are type-safe and secure. For applications of delegates, see [Delegates](../../programming-guide/delegates/index.md) and [Generic Delegates](../../programming-guide/generics/generic-delegates.md). Delegates are the basis for [Events](../../programming-guide/events/index.md). A delegate can be instantiated by associating it either with a named or anonymous method.
 
 The delegate must be instantiated with a method or lambda expression that has a compatible return type and input parameters. For more information on the degree of variance that is allowed in the method signature, see [Variance in Delegates](../../programming-guide/concepts/covariance-contravariance/using-variance-in-delegates.md). For use with anonymous methods, the delegate and the code to be associated with it are declared together.