Clarify how string enums are created in the Data preferences page

getting_started/workflow/best_practices/data_preferences.rst

@@ -273,10 +273,10 @@ limited only by their imagination.
 Enumerations: int vs. string
 ----------------------------
 
-Most languages offer an enumeration type option. GDScript is no different,
-but unlike most other languages, it allows one to use either integers or
-strings for the enum values. The question then arises, "which should one
-use?"
+Most languages offer an enumeration type option. GDScript is no different, but
+unlike most other languages, it allows one to use either integers or strings for
+the enum values (the latter only when using the ``export`` keyword in GDScript).
+The question then arises, "which should one use?"
 
 The short answer is, "whichever you are more comfortable with." This
 is a feature specific to GDScript and not Godot scripting in general;