Configure direct-delivery incoming email for self-hosted sites with Mail-Receiver

어떻게 깨뜨렸는지 설명해 주시겠어요? 이 값 주위에 인용 부호가 있든 없든 결과는 차이가 없습니다:

[2] pry(main)> YAML::load("env:\n  DISCOURSE_BASE_URL: 'https://discourse.example.com'")
=> {"env"=>{"DISCOURSE_BASE_URL"=>"https://discourse.example.com"}}

[3] pry(main)> YAML::load("env:\n  DISCOURSE_BASE_URL: https://discourse.example.com")
=> {"env"=>{"DISCOURSE_BASE_URL"=>"https://discourse.example.com"}}