Translate Complete(kr) : Action Cable Overview - 1st' Modified

[yhk1038]

Summary

Translated to korean for ActionCable Overview based on rails new version 5.2

Other Information

• based repository rorlakr/rails-guides
• based branch 5.2-ko
• a file changed: ~/guide/source/ko/action_cable_overview.md
• original guide: Action Cable Overview - Ruby on Rails Guides v5.2
• Modified by feedback of pull request: #73

[wagurano]

73 풀리퀘스트와 같은 풀리퀘스트인가요?

[yhk1038]

엇 실수로 같은 풀리퀘스트가 또 올라간 것 같습니다. 죄송합니다. 닫겠습니다;;;