readme: add language tag

Hi,

as part of the #Hacktoberfest [2023](https://github.com/huggingface/hub-docs/issues/986) this MR extends the dataset metadata and adds a language tag.

Happy merging!

README.md

@@ -13,7 +13,9 @@ dataset_info:
     num_bytes: 14955814.758369517
     num_examples: 40281
   download_size: 95987466
-  dataset_size: 149554806.0
+  dataset_size: 149554806
+language:
+- tr
 ---
 # Dataset Card for "turkishReviews-ds-mini"