Update changelogs from fern repo (#818)

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

Author: fern-support

fern/products/sdks/overview/typescript/changelog/2025-09-08.mdx renamed to fern/products/sdks/overview/typescript/changelog/2025-09-15.mdx

@@ -7,7 +7,7 @@ This prevents compilation errors in the TypeScript SDK.
 **`(feat):`** Generate `Request` and `Response` types variations for types that have readonly and/or writeonly properties.
 For example, a type `User` will have a `User.Request` type that omits readonly properties and a `User.Response` type that omits writeonly properties.
 
-Set `generateReadWriteOnlyTypes` to `true` in the `config` of your generator configuration to enable this feature.
+Set `experimentalGenerateReadWriteOnlyTypes` to `true` in the `config` of your generator configuration to enable this feature.
 ```ts
 import { User, FooClient } from "foo";