let installer blurb point to community page

being too specific about it requires more maintenance (or otherwise
produced more confusion and churn), since these points of contact change
over time.

scripts/install-multi-user.sh

@@ -99,11 +99,7 @@ is_os_darwin() {
 contact_us() {
     echo "You can open an issue at https://github.com/nixos/nix/issues"
     echo ""
-    echo "Or feel free to contact the team:"
-    echo " - Matrix: #nix:nixos.org"
-    echo " - IRC: in #nixos on irc.libera.chat"
-    echo " - twitter: @nixos_org"
-    echo " - forum: https://discourse.nixos.org"
+    echo "Or get in touch with the community: https://nixos.org/community"
 }
 get_help() {
     echo "We'd love to help if you need it."