add autoevaluate config

add config per the suggestion of the [autoevaluate space](https://huggingface.co/spaces/autoevaluate/model-evaluator)

README.md

@@ -19,6 +19,15 @@ task_ids:
 - news-articles-summarization
 paperswithcode_id: cnn-daily-mail-1
 pretty_name: CNN / Daily Mail
+train-eval-index:
+- config: 3.0.0
+  task: summarization
+  task_id: summarization
+  splits:
+    eval_split: test
+  col_mapping:
+    article: text
+    highlights: target
 ---
 # Dataset Card for CNN Dailymail Dataset