How to upgrade to Ubuntu 19.04 Disco Dingo from 18.04/18.10 ?

Ubuntu 19.04 disco dingo is a new release in the Ubuntu line-up. Ubuntu 18.04 is an LTS (long term support) release, so it gets support for the next 5 years after the release. Ubuntu 19.04 is not an LTS release and will only be supported up to 9 months