Use group.<name> instead of luckperms.group.<name> to indicate group membership

bukkit/src/main/java/me/lucko/luckperms/BukkitConfig.java

@@ -47,7 +47,7 @@ public class BukkitConfig implements LPConfiguration {
 
     @Override
     public String getDefaultGroupNode() {
-        return "luckperms.group." + configuration.getString("default-group", "default");
+        return "group." + configuration.getString("default-group", "default");
     }
 
     @Override

bukkit/src/main/resources/config.yml

@@ -3,7 +3,7 @@
 # The name of the server, used for server specific permissions. Set to 'global' to disable.
 server: global
 
-# The default group assigned to all user on join. e.g. a value of "default" = luckperms.group.default
+# The default group assigned to all user on join.
 default-group: default
 
 # If users on this server should have their global permissions/groups applied.