Add Claper to Polls and Events (#3280)

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

README.md

@@ -1575,6 +1575,7 @@ _Related: [Booking and Scheduling](#booking-and-scheduling)_
 - [Bitpoll](https://github.com/fsinfuhh/Bitpoll) - A web application for scheduling meetings and general polling. ([Demo](https://bitpoll.mafiasi.de/)) `GPL-3.0` `Python`
 - [Calagator](https://calagator.org/) - Event aggregator. ([Source Code](https://github.com/calagator/calagator)) `MIT` `Ruby`
 - [Christmas Community](https://github.com/Wingysam/Christmas-Community) - Create a simple place for your entire family to use to find gifts that people want, and to avoid double-gifting. `AGPL-3.0` `Docker/Nodejs`
+- [Claper](https://claper.co/) - The ultimate tool to interact with your audience. An open-source alternative to Slido, AhaSlides and Mentimeter. ([Source Code](https://github.com/ClaperCo/Claper)) `GPL-3.0` `Elixir/Docker`
 - [ClearFlask](https://clearflask.com) - Community-feedback tool for managing incoming feedback and prioritizing a public roadmap. Alternative to Canny, UserVoice, Upvoty. ([Demo](https://product.clearflask.com), [Source Code](https://github.com/clearflask/clearflask)) `AGPL-3.0` `Docker`
 - [Croodle](https://github.com/jelhan/croodle) - Croodle is an end-to-end encrypted web application to schedule a date or to do a poll on any topic. `MIT` `Javascript`
 - [dudle](http://primelife.ercim.eu/results/opensource/63-dudle) - Online scheduling application. ([Demo](https://dudle.inf.tu-dresden.de/), [Source Code](https://github.com/kellerben/dudle)) `AGPL-3.0` `Ruby`