Add vikunja to task management

README.md

@@ -1406,6 +1406,7 @@ See https://staticsitegenerators.net and https://www.staticgen.com
 - [todo](https://github.com/prologic/todo) - Simple todo list manager. ([Demo](https://todo.mills.io)) `MIT` `Go`
 - [todoMini](https://www.todomini.app/) - Mobile friendly zero-feature TODO list web app. Unix philosophy. ([Demo](https://appmini.github.io/todoMini/?demo), [Source Code](https://github.com/appMini/todoMini)) `GPL-3.0` `PHP/Clojure`
 - [Tracks](http://www.getontracks.org/) - Web-based application to help you implement David Allen’s [Getting Things Done™](https://en.wikipedia.org/wiki/Getting_Things_Done) methodology. ([Source Code](https://github.com/TracksApp/tracks)) `GPL-2.0` `Ruby`
+- [Vikunja](https://vikunja.io/) - The to-do app to organize your life. ([Demo](https://try.vikunja.io/login), [Source Code](https://kolaente.dev/vikunja/)) `GPL-3.0` `Go`
 - [Volition](https://github.com/usevolition/volition) - Opinionated open-source task management. `MIT` `Ruby`
 - [Wekan](https://wekan.github.io/) - Open-source Trello-like kanban. ([Demo](https://oasis.sandstorm.io/appdemo/m86q05rdvj14yvn78ghaxynqz7u2svw6rnttptxx49g1785cdv1h), [Source Code](https://github.com/wekan/wekan)) `MIT` `Nodejs`