Structure types: moved an example for clarity (#22230)

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

@@ -24,11 +24,7 @@ Because structure types have value semantics, we recommend you to define *immuta
 
 ## `readonly` struct
 
-Beginning with C# 7.2, you use the `readonly` modifier to declare that a structure type is immutable:
-
-[!code-csharp[readonly struct](snippets/shared/StructType.cs#ReadonlyStruct)]
-
-All data members of a `readonly` struct must be read-only as follows:
+Beginning with C# 7.2, you use the `readonly` modifier to declare that a structure type is immutable. All data members of a `readonly` struct must be read-only as follows:
 
 - Any field declaration must have the [`readonly` modifier](../keywords/readonly.md)
 - Any property, including auto-implemented ones, must be read-only. In C# 9.0 and later, a property may have an [`init` accessor](../../whats-new/csharp-9.md#init-only-setters).
@@ -38,6 +34,10 @@ That guarantees that no member of a `readonly` struct modifies the state of the
 > [!NOTE]
 > In a `readonly` struct, a data member of a mutable reference type still can mutate its own state. For example, you can't replace a <xref:System.Collections.Generic.List%601> instance, but you can add new elements to it.
 
+The following code defines a `readonly` struct with init-only property setters, available in C# 9.0 and later:
+
+[!code-csharp[readonly struct](snippets/shared/StructType.cs#ReadonlyStruct)]
+
 ## `readonly` instance members
 
 Beginning with C# 8.0, you can also use the `readonly` modifier to declare that an instance member doesn't modify the state of a struct. If you can't declare the whole structure type as `readonly`, use the `readonly` modifier to mark the instance members that don't modify the state of the struct.