Add deprecation warning

It'd be better to move away from canonical datasets and push the usage towards datasets hosted under an organisation.

We are already doing this with multilingual_librispeech, only makes sense to do this for common voice as well.

Note: That currently I link to the latest available CV split on the hub CV11, this should be updated when we add CV12.

cc:

@albertvillanova



@polinaeterna



@sanchit-gandhi

common_voice.py

@@ -16,6 +16,7 @@
 
 
 import os
+import warnings
 
 import datasets
 from datasets.tasks import AutomaticSpeechRecognition
@@ -629,6 +630,15 @@ class CommonVoice(datasets.GeneratorBasedBuilder):
     ]
 
     def _info(self):
+
+        warnings.warn(
+            """
+            This version of the Common Voice dataset is deprecated.
+            You can download the latest one with
+            >>> load_dataset(\"mozilla-foundation/common_voice_11_0\", \"en\")
+            """
+        )
+        
         features = datasets.Features(
             {
                 "client_id": datasets.Value("string"),