new: [vps] use ssh key commentary to store compose type

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/vps

@@ -226,7 +226,7 @@ mailcow:install-backup() {
         return 1
     fi
 
-
+    export KEY_BACKUP_ID="mailcow"
     export MYSQL_ROOT_PASSWORD
     export MYSQL_CONTAINER
     export BACKUP_SERVER
@@ -369,7 +369,7 @@ EOF
     info "You can run this following command from an host having admin access to $dest:"
     echo "   (Or send it to a backup admin of $dest)" >&2
     public_key=$(ssh-keygen -y -f <(e "$private_key"$'\n'))
-    echo "ssh ${ssh_options[@]} myadmin@$dest ssh-key add '$public_key ${service_name}@$host'"
+    echo "ssh ${ssh_options[@]} myadmin@$dest ssh-key add '$public_key compose@$host'"
 }