Fifth Korean l10n work for release-1.15 (#16231)

* Translate `concepts/scheduling/_index.md` to Korean (#16072)
* Translate concepts/workloads/controllers/replicaset.md in Korean (#16070)
* Update outdated content in dev-1.15-ko.5 (#16162)
* Translate using-api/client-libraries into korean (#16182)
* ko: translate concepts/cluster-administration/proxies (#16030)
* Translate concepts/workloads/controllers/deployment.md in Korean (#16113)

Co-Authored-By: Seokho Son <shsongist@gmail.com>
Co-Authored-By: Eden <longlg88@naver.com>
Co-Authored-By: Yoon <learder@gmail.com>
Co-Authored-By: Sunghoon Kang <me@devholic.io>
Co-Authored-By: Yuk, Yongsu <ysyukr@gmail.com>
Co-Authored-By: June Yi <gochist@gmail.com>

content/ko/examples/controllers/frontend.yaml

@@ -0,0 +1,21 @@
+apiVersion: apps/v1
+kind: ReplicaSet
+metadata:
+  name: frontend
+  labels:
+    app: guestbook
+    tier: frontend
+spec:
+  # 케이스에 따라 레플리카를 수정한다.
+  replicas: 3
+  selector:
+    matchLabels:
+      tier: frontend
+  template:
+    metadata:
+      labels:
+        tier: frontend
+    spec:
+      containers:
+      - name: php-redis
+        image: gcr.io/google_samples/gb-frontend:v3