added FlatPress blogging engine (#3281)

README.md

@@ -223,6 +223,7 @@ _See also: [WeblogMatrix](https://www.weblogmatrix.org/)_
 - [Castopod](https://castopod.org) - A podcast management hosting platform that includes the latest podcast 2.0 standards, an automated Fediverse feed, analytics, an embeddable player, and more. ([Source Code](https://code.castopod.org/adaures/castopod)) `AGPL-3.0` `PHP`
 - [Chyrp Lite](https://chyrplite.net) - Extra-awesome, extra-lightweight blog engine. ([Source Code](https://github.com/xenocrat/chyrp-lite)) `BSD-3-Clause` `PHP`
 - [Dotclear](https://dotclear.org/) - Take control over your blog. ([Source Code](https://git.dotclear.org/dev/dotclear)) `GPL-2.0` `PHP`
+- [FlatPress](https://flatpress.org/) - A lightweight, easy-to-set-up flat-file blogging engine. ([Source Code](https://github.com/flatpressblog/flatpress)) `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`
 - [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`