Add collAnon apps

Resolves #276.

README.md

@@ -56,6 +56,7 @@ _Source:_ [Google Developers - Progressive Web Apps](https://developers.google.c
 * [Chitchatter](https://chitchatter.im/): Secure peer-to-peer chat that is serverless, decentralized, and ephemeral
 * [Chrome Developer Summit](https://developers.google.com/): Google Developers
 * [Closerintime](https://closerinti.me): #closerintime
+* [collAnon](https://collanon.app): Private discussions, perspectives exchange and a simple Gantt calendar.
 * [ColorBeta](https://colorbeta.com): Advanced CSS Gradient Generator
 * [Colosseum](https://naramsim.github.io/Colosseum/): Displays Pokemons in a beautiful way
 * [ComputerBase](https://www.computerbase.de/): German IT news site.