Added Seatsurfing desk booking (#3645)

Co-authored-by: nodiscc <nodiscc@gmail.com>

README.md

@@ -260,6 +260,7 @@ _Related: [Polls and Events](#polls-and-events)_
 - [Cal.com](https://cal.com/) - The open-source online appointment scheduling system. ([Demo](https://app.cal.com/bailey), [Source Code](https://github.com/calcom/cal.com)) `MIT` `Nodejs`
 - [Easy!Appointments](https://easyappointments.org/) - A highly customizable web application that allows your customers to book appointments with you via the web. ([Demo](https://easyappointments.org/demo/), [Source Code](https://github.com/alextselegidis/easyappointments)) `GPL-3.0` `PHP`
 - [QloApps](https://qloapps.com/) - An open-source, customizable and intuitive web-based hotel reservation system and a booking engine. ([Demo](https://demo.qloapps.com/), [Source Code](https://github.com/webkul/hotelcommerce)) `OSL-3.0` `PHP`
+- [Seatsurfing](https://seatsurfing.app/) - Webbased app to book seats, desks and rooms for offices. ([Demo](https://seatsurfing.app/get-started/), [Source Code](https://github.com/seatsurfing/backend)) `GPL-3.0` `Docker`
 
 
 ### Bookmarks and Link Sharing