Add Haven to blogging section (#2655)

README.md

@@ -112,6 +112,7 @@ _See also: [WeblogMatrix](https://www.weblogmatrix.org/)_
 - [Dotclear](https://dotclear.org/) - Take control over your blog. ([Source Code](https://hg.dotclear.org/dotclear)) `GPL-2.0` `PHP`
 - [Formtools](https://formtools.org/) - Powerful, flexible, free and open source PHP/MySQL script to manage your forms and data. ([Source Code](https://github.com/formtools)) `GPL-2.0` `PHP`
 - [Ghost](https://ghost.org/) - Just a blogging platform. ([Source Code](https://github.com/TryGhost/Ghost)) `MIT` `Nodejs`
+- [Haven](https://havenweb.org/) - Private blogging system with markdown editing and built in RSS reader. ([Demo](https://havenweb.org/demo.html), [Source Code](https://github.com/havenweb/haven)) `MIT` `Ruby`
 - [Hexo](https://hexo.io/) - Fast, simple and powerful blog framework. ([Source Code](https://github.com/hexojs/hexo)) `MIT` `Nodejs`
 - [Hotglue](https://hotglue.me/) - Freehand CMS which allows to construct websites directly in a web-browser. It uses flat files for storage and provides an intuitive GUI. ([Demo](https://hotglue.me/demo/), [Source Code](https://github.com/k0a1a/hotglue2)) `GPL-3.0` `PHP`
 - [htmly](https://www.htmly.com/) - Databaseless Blogging Platform (Flat-File Blog). ([Demo](https://demo.htmly.com/), [Source Code](https://github.com/danpros/htmly)) `GPL-2.0` `PHP`