Add Dalton Plan to Learning and Courses (#2887)

README.md

@@ -1084,6 +1084,7 @@ _Related: [Groupware](#groupware)_
 
 - [Canvas LMS](https://www.canvaslms.com/) - Canvas is the trusted, open-source learning management system (LMS) that is revolutionizing the way we educate. ([Demo](https://canvas.instructure.com/register), [Source Code](https://github.com/instructure/canvas-lms)) `AGPL-3.0` `Ruby`
 - [Chamilo LMS](https://chamilo.org/) - Chamilo LMS allows you to create a virtual campus for the provision of online or semi-online training. ([Source Code](https://github.com/chamilo/chamilo-lms)) `GPL-3.0` `PHP`
+- [Dalton Plan](https://daltonplan.com) - Dalton Plan is a modern adoption of a free teaching method developed by Helen Parkhurst in the 20th century. ([Source Code](https://git.io/daltonplan)) `AGPL-3.0` `PHP`
 - [edX](https://www.edx.org/) - The Open edX platform is open-source code that powers edX.org. ([Source Code](https://github.com/edx/)) `AGPL-3.0` `Python`
 - [Gibbon](https://www.gibbonedu.org/) - The flexible, open source school management platform designed to make life better for teachers, students, parents and leaders. ([Source Code](https://github.com/GibbonEdu/core)) `GPL-3.0` `PHP`
 - [ILIAS](https://www.ilias.de) - ILIAS is the Learning Management System that can cope with anything you throw at it. ([Demo](https://demo.ilias.de), [Source Code](https://github.com/ILIAS-eLearning/ILIAS)) `GPL-3.0` `PHP`