Add task categories and improve metadata

This PR adds `task_categories: text-generation` to the dataset metadata to improve its discoverability on the Hugging Face Hub. It also maintains the existing documentation, including the paper abstract and sample usage snippets.

README.md

@@ -1,4 +1,9 @@
 ---
+license: mit
+task_categories:
+- text-generation
+size_categories:
+- 10K<n<100K
 dataset_info:
   features:
   - name: task
@@ -24,9 +29,6 @@ configs:
   data_files:
   - split: train
     path: data/train-*
-license: mit
-size_categories:
-- 10K<n<100K
 ---
 
 # How Do Language Models Compose Functions?