Eighth Korean l10n work for release 1.18

- Translate tasks/administer-cluster/declare-network-policy in Korean (#22526)
- Translate tasks/debug-application-cluster/debug-init-containers in Korean (#22608)
- Fix a missing markdown syntax to enable external link (#22661)
- Translate tasks/administer-cluster/change-pv-reclaim-policy in Korean (#22551)
- Update docs/contribute/participate/ for Korean (#22605)
- Update outdated files in dev-1.18-ko.8 (#22466)
- Translate tasks/administer-cluster/dns-custom-nameservers in Korean (#22524)

Co-authored-by: Daehyun Paik <paik@a30a.dev>
Co-authored-by: Jerry Park <jaehwa@gmail.com>
Co-authored-by: bluefriday <bluefriday86@gmail.com>
Co-authored-by: June Yi <june.yi@samsung.com>
Co-authored-by: Jesang Myung <jesang.myung@gmail.com>
Co-authored-by: Seokho Son <shsongist@gmail.com>

content/ko/docs/tasks/_index.md

@@ -11,9 +11,5 @@ content_type: concept
 보여준다. 한 태스크 페이지는 일반적으로 여러 단계로 이루어진 짧은
 시퀀스를 제공함으로써, 하나의 일을 수행하는 방법을 보여준다.
 
-
-## {{% heading "whatsnext" %}}
-
-
 만약 태스크 페이지를 작성하고 싶다면,
 [문서 풀 리퀘스트(Pull Request) 생성하기](/ko/docs/contribute/new-content/new-content/)를 참조한다.