docs: remove link to Google Group

.gitlab/issue_templates/feature_request.md

@@ -5,7 +5,7 @@
 ## Implementation ideas
 
 (If you have any implementation ideas, they can go here.)
-(Any design change proposal could be also discussed on the _to be continuous_ Google Group: https://groups.google.com/g/tbc-dev.)
+(Any design change proposal could be also discussed on the _to be continuous_ Discord server.)
 
 
 /label ~"kind/enhancement" ~"status/needs-investigation"