DOC Update tree.rst about lack of support of categorical data (scikit-learn#18106)

Author: hiteshsom

doc/modules/tree.rst

@@ -33,8 +33,9 @@ Some advantages of decision trees are:
     - The cost of using the tree (i.e., predicting data) is logarithmic in the
       number of data points used to train the tree.
 
-    - Able to handle both numerical and categorical data. Other techniques
-      are usually specialised in analysing datasets that have only one type
+    - Able to handle both numerical and categorical data. However scikit-learn 
+      implementation does not support categorical variables for now. Other 
+      techniques are usually specialised in analysing datasets that have only one type
       of variable. See :ref:`algorithms <tree_algorithms>` for more
       information.