docs(kr): add a translation of an example in actions.md of guide docs (#1761)

* Add a translation of an example in actions.md of guide docs

* Update docs/kr/guide/actions.md

Co-authored-by: ChangJoo Park(박창주) <pcjpcj2@gmail.com>

* Apply suggestions from code review

Co-authored-by: ChangJoo Park(박창주) <pcjpcj2@gmail.com>

Co-authored-by: ChangJoo Park(박창주) <pcjpcj2@gmail.com>

docs/kr/guide/actions.md

@@ -111,6 +111,9 @@ export default {
   methods: {
     ...mapActions([
       'increment' // this.increment()을 this.$store.dispatch('increment')에 매핑
+
+      // mapActions는 페이로드를 지원합니다.
+      'incrementBy' // this.incrementBy(amount)를 this.$store.dispatch('incrementBy', amount)에 매핑
     ]),
     ...mapActions({
       add: 'increment' // this.add()을 this.$store.dispatch('increment')에 매핑