By Joyce Lee SEOUL (Reuters) – Kakao Corp’s co-CEO Namkoong Whon resigned on Wednesday as South Korea’s largest mobile chat app sought to defuse public anger over a massive outage that left tens of millions without access to a wide range of services. The company has pledged to increase investment to ensure continuity at the data centres it uses amid growing concern about the app’s market dominance in Asia’s fourth-largest economy. Namkoong’s resignation comes only seven months after he took the top job and leaves co-CEO Hong Euntaek, appointed in July, as sole CEO. The two apologised for the o…