Tenth Korean l10n work for release 1.18

- Translate concepts/extend-kubenetes/service-catalog.md in Korean (#23233)
- Translate concepts/configuration/secret.md into Korean (#23110)
- Translate tasks/extend-kubernetes/setup-extension-api-server.md into … (#22574)
- Update outdated files in dev-1.18-ko.10 branch (#23013)

Co-authored-by: Seokho Son <shsongist@gmail.com>
Co-authored-by: Jerry Park <jaehwa@gmail.com>
Co-authored-by: santachopa <santachopa@naver.com>

content/ko/docs/concepts/extend-kubernetes/operator.md

@@ -11,9 +11,6 @@ weight: 30
 사용하여 애플리케이션 및 해당 컴포넌트를 관리하는 쿠버네티스의 소프트웨어 익스텐션이다. 오퍼레이터는
 쿠버네티스 원칙, 특히 [컨트롤 루프](/ko/docs/concepts/#쿠버네티스-컨트롤-플레인)를 따른다.
 
-
-
-
 <!-- body -->
 
 ## 동기 부여