Update README.md (#538)

doc/02_Installation/README.md

@@ -78,8 +78,7 @@ Following options to prepare the customer class are available:
 
 As starting point this [class definition](https://github.com/pimcore/customer-data-framework/blob/master/install/class_source/optional/class_Customer_export.json) can be used.
 
-Note that the class doesn't need to contain the attributes as field definitions. You can also just add the fields to your specific class implementation interface by adding getters. You **must** also enable the _Generate Type Declarations_ options on the `Customer` class for the attributes to be compatible with the `Interface`.
-
+Note that the class doesn't need to contain the attributes as field definitions. You can also just add the fields to your specific class implementation interface by adding getters.
 
   Example
   ```php