List all possible variable types in class Variable docstring

Author: Thierry RAMORASOAVINA

khiops/core/dictionary.py

@@ -952,6 +952,10 @@ class Variable:
         True if the variable is used.
     type : str
         Variable type.
+        It can be either native (``Categorical``, ``Numerical``, ``Time``,
+        ``Date``, ``Timestamp``, ``TimestampTZ``, ``Text``, ``TextList``)
+        complex (``Structure``)
+        or relational (``Entity``, ``Table``)
     object_type : str
         Type complement for the ``Table`` and ``Entity`` types.
     structure_type : str