Update dataset card after split cleanup

README.md

@@ -31,7 +31,6 @@ Predefined folds are included under:
 folds/microscopy_lurcher/fold-<fold>/
   train.jsonl
   val.jsonl
-  val_selected.jsonl
   test.jsonl
 ```
 
@@ -41,7 +40,7 @@ Each row has a path relative to the dataset repository root and a normalized cla
 {"image_path":"images/microscopy_lurcher/lurcher/5917/example.jpg","class":"lurcher"}
 ```
 
-`train.jsonl` is the active-learning candidate pool. `val_selected.jsonl` is the validation subset used by the APT code when present; otherwise the code falls back to `val.jsonl`. `test.jsonl` is the held-out evaluation split.
+`train.jsonl` is the active-learning candidate pool. `val.jsonl` is the validation split used by the APT code. `test.jsonl` is the held-out evaluation split.
 
 ## Metadata