Add docs to useResponseAsReturnType

Author: lsuski

docs/generators/kotlin.md

@@ -50,6 +50,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |supportAndroidApiLevel25AndBelow|[WARNING] This flag will generate code that has a known security vulnerability. It uses `kotlin.io.createTempFile` instead of `java.nio.file.Files.createTempFile` in order to support Android API level 25 and below. For more info, please check the following links https://github.com/OpenAPITools/openapi-generator/security/advisories/GHSA-23x4-m842-fmwf, https://github.com/OpenAPITools/openapi-generator/pull/9284| |false|
 |useCoroutines|Whether to use the Coroutines adapter with the retrofit2 library.| |false|
 |useNonAsciiHeaders|Allow to use non-ascii headers with the okhttp library| |false|
+|useResponseAsReturnType| When using retrofit2 and coroutines, use `Response<T>` as return type instead of `T`.| |true|
 |useRxJava3|Whether to use the RxJava3 adapter with the retrofit2 library.| |false|
 |useSettingsGradle|Whether the project uses settings.gradle.| |false|
 |useSpringBoot3|Whether to use the Spring Boot 3 with the jvm-spring-webclient library.| |false|