show image badge in org-mode

I started to use org-mode for readme files. One of the issues was: how to show image badges, i.e. for travis-ci. For later reference this is how it is done:

[[https://travis-ci.com/ABC/PROJECT][file:https://travis-ci.com/ABC/PROJECT.svg?token=XXX&branch=master]]

The trick is the file: in front of the url.