Emphasize script classes over custom types in Making plugins

Custom types were more relevant in the early Godot 3.x days,
but nowadays, script classes should be preferred whenever possible
(i.e. in any non-C# language).

tutorials/plugins/editor/making_plugins.rst

@@ -153,10 +153,14 @@ custom behavior.
 
 .. warning::
 
-  Nodes added via an EditorPlugin are "CustomType" nodes. While they work
+  Nodes added via an EditorPlugin's :ref:`add_custom_type() <class_EditorPlugin_method_add_custom_type>`
+  function are "custom type" nodes. While they work
   with any scripting language, they have fewer features than
   :ref:`the Script Class system <doc_gdscript_basics_class_name>`. If you
-  are writing GDScript or NativeScript, we recommend using Script Classes instead.
+  are using GDScript or GDExtension, we recommend using Script Classes instead.
+
+  Custom types are still the recommended approach for C#, as it does not support
+  Script Classes.
 
 To create a new node type, you can use the function
 :ref:`add_custom_type() <class_EditorPlugin_method_add_custom_type>` from the
@@ -231,12 +235,19 @@ dialog. For that, change the ``custom_node.gd`` script to the following:
     func _enter_tree():
         # Initialization of the plugin goes here.
         # Add the new type with a name, a parent type, a script and an icon.
+        #
+        # NOTE: If `my_button.gd` uses `class_name MyButton`, do not call `add_custom_type()`
+        # and leave this function empty instead with `pass`.
+        # Script Classes and custom types will conflict if the same name is used for both.
         add_custom_type("MyButton", "Button", preload("my_button.gd"), preload("icon.png"))
 
 
     func _exit_tree():
         # Clean-up of the plugin goes here.
         # Always remember to remove it from the engine when deactivated.
+        #
+        # NOTE: This should not be called if Script Classes are used instead.
+        # In this case, leave this function empty with `pass`.
         remove_custom_type("MyButton")
 
  .. code-tab:: csharp