Fix number of samples in README

The number of samples in each split is incorrect in the README. This results in the following error when loading the dataset:
```
datasets.utils.info_utils.NonMatchingSplitsSizesError: [{'expected': SplitInfo(name='train', num_bytes=0, num_examples=145008, shard_lengths=None, dataset_name=None), 'recorded': SplitInfo(name='train', num_bytes=3567896931, num_examples=145009, shard_lengths=[30000, 30000, 30000, 20000, 30000, 5009], dataset_name='nor_hand-v2-line')}, {'expected': SplitInfo(name='validation', num_bytes=0, num_examples=14965, shard_lengths=None, dataset_name=None), 'recorded': SplitInfo(name='validation', num_bytes=364518531, num_examples=14966, shard_lengths=None, dataset_name='nor_hand-v2-line')}, {'expected': SplitInfo(name='test', num_bytes=0, num_examples=1792, shard_lengths=None, dataset_name=None), 'recorded': SplitInfo(name='test', num_bytes=31054952, num_examples=1562, shard_lengths=None, dataset_name='nor_hand-v2-line')}]
```

The large difference in the test set is expected, as the split was changed to match the NorHand v3 test set when it was released.

README.md

@@ -13,12 +13,12 @@ dataset_info:
     dtype: string
   splits:
   - name: train
-    num_examples: 145008
+    num_examples: 145009
   - name: validation
-    num_examples: 14965
+    num_examples: 14966
   - name: test
-    num_examples: 1792
-  dataset_size: 161831
+    num_examples: 1562
+  dataset_size: 161537
 tags:
 - atr
 - htr