only mention "make" command for "cookieplone" generated addons

Author: petschki

docs/developer-guide/create-a-backend-add-on.md

@@ -139,13 +139,9 @@ Available mr.bob templates:
  All templates below `addon` can be added to your newly created addon with:
 
  ```shell
- uvx plonecli add <subtemplate>
+ make add <subtemplate>
  ```
 
-```{note}
-When you have created a project with `cookieplone`, then you can simply do `make add <subtemplate>` inside the {file}`backend` folder.
-```
-
 Currently documented subtemplates:
 
 - behavior: {ref}`backend-behaviors-label`