Update README.md

README.md

@@ -11,11 +11,11 @@ columns:
   - name: problem_text
     type: string
   - name: choices
-    type: list
+    type: list[string]
   - name: text_only
     type: bool
   - name: answer
-    type: list
+    type: list[string]
   - name: comment
     type: string
   - name: num_images