add mailinglist to contributing

.github/CONTRIBUTING.md

@@ -31,6 +31,6 @@ Do not report crashes in the GitHub issue tracker. NewPipe has an automated cras
 
 ## Communication
 
-* I hereby declare our Slack channel as dead!!! There are no plans on building a new chat, but if there is interest on creating one and keeping it alive, I'd be pleased to create one again. 
+* WE DO NOW HAVE A MAILING LIST: [newpipe@list.schabi.org](https://list.schabi.org/cgi-bin/mailman/listinfo/newpipe).
 * If you want to get in contact with me or one of our other contributors you can send me an email at tnp(at)schabi.org
 * Feel free to post suggestions, changes, ideas etc!