Add "ClearFlask" to "Polls and Events" (#2731)

README.md

@@ -1366,6 +1366,7 @@ _Related: [Monitoring](#monitoring)_
 _Related: [Booking and Scheduling](#booking-and-scheduling)_
 
 - [Calagator](https://calagator.org/) - Event aggregator. ([Source Code](https://github.com/calagator/calagator)) `MIT` `Ruby`
+- [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`
 - [Clerk](https://github.com/AppMini/Clerk) - Simple event logger to keep track of periodic events, habits, etc. as they occur. `GPL-3.0` `PHP`
 - [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`