Add task category to dataset card

This PR adds the missing `task_categories` field to the dataset metadata, setting it to `question-answering` for better discoverability on the Hugging Face Hub. The existing dataset card content remains unchanged.

README.md

@@ -1,7 +1,7 @@
 ---
-license: cc-by-4.0
 language:
 - en
+license: cc-by-4.0
 pretty_name: DebateLedger
 tags:
 - multi-agent-debate
@@ -10,6 +10,8 @@ tags:
 - collapse
 - correction
 viewer: false
+task_categories:
+- question-answering
 ---
 
 # DebateLedger
@@ -106,4 +108,4 @@ year={2026}
 ## License
 
 CC BY 4.0. Questions come from public benchmarks (MMLU-Pro, GPQA, GSM8K,
-ARC-Challenge, TruthfulQA) and remain subject to their licenses.
+ARC-Challenge, TruthfulQA) and remain subject to their licenses.