Update README.md

Describe the dataset information, where it has abbreviated from, and how it has been modified.

README.md

@@ -1,3 +1,21 @@
 ---
 license: gpl-3.0
+task_categories:
+- text-classification
+language:
+- zh
+size_categories:
+- 1K<n<10K
 ---
+
+This dataset is copied from [CLUE](https://github.com/CLUEbenchmark/OCNLI/tree/main/data/ocnli) with certain modifications.
+The paper of CLUE is [OCNLI](https://arxiv.org/abs/2010.05444).
+
+The modifications are:
+1. Transform json file to csv file.
+2. Encoding in UTF-8.
+3. Remove data entries whose label value is '-'.
+4. Replace label values, 'neutral' to 1, 'entailment' to 0, and 'contradiction' to 2.
+
+ocnli_train_std.csv comes from train.50k.json.
+ocnli_test_std.csv comes from dev.json.