Fix typo in ko.po (#2844)

Day 4 is translated into 1일차(Day 1)

Author: handohun

po/ko.po

@@ -565,7 +565,7 @@ msgstr "연습문제: Protobuf 파싱"
 #: src/SUMMARY.md
 #, fuzzy
 msgid "Day 4: Morning"
-msgstr "1일차 오전"
+msgstr "4일차 오전"
 
 #: src/SUMMARY.md src/iterators.md
 msgid "Iterators"
@@ -636,7 +636,7 @@ msgstr "룬 알고리즘"
 #: src/SUMMARY.md
 #, fuzzy
 msgid "Day 4: Afternoon"
-msgstr "1일차 오후"
+msgstr "4일차 오후"
 
 #: src/SUMMARY.md src/error-handling.md
 msgid "Error Handling"