fix(nlc): add deprecation warning

add deprecation warning to NLC constructor

fix #9624

ibm_watson/natural_language_classifier_v1.py

@@ -84,6 +84,15 @@ def classify(self, classifier_id: str, text: str,
         :rtype: DetailedResponse with `dict` result representing a `Classification` object
         """
 
+        print(
+            """
+            On 9 August 2021, IBM announced the deprecation of the Natural Language Classifier service.
+            The service will no longer be available from 8 August 2022. As of 9 September 2021, you will not be able to create new instances. 
+            Existing instances will be supported until 8 August 2022. Any instance that still exists on that date will be deleted.
+            For more information, see https://cloud.ibm.com/docs/natural-language-classifier?topic=natural-language-classifier-migrating
+            """
+        )
+
         if classifier_id is None:
             raise ValueError('classifier_id must be provided')
         if text is None: