man orage shows: HOMEPAGE http://www.xfce.org/projects/orage/ This URL does not exist anymore.
I can't find a dedicated page for Orage on https://docs.xfce.org/ , https://wiki.xfce.org/ , or https://goodies.xfce.org/ . Even https://xfce.org/projects doesn't have a "Learn More" page for Orage. Maybe the link could be removed, or the link changed to the repository at https://git.xfce.org/apps/orage/ .
The orage project is not maintained anymore and has been archived. Closing bugs.