Add JSONL preview samples

jsonl_preview/manifest.json

@@ -0,0 +1,30 @@
+{
+  "random_shuffle": {
+    "train": {
+      "rows": 20,
+      "file": "random_shuffle_train_first_20.jsonl"
+    },
+    "validation": {
+      "rows": 20,
+      "file": "random_shuffle_validation_first_20.jsonl"
+    },
+    "test": {
+      "rows": 20,
+      "file": "random_shuffle_test_first_20.jsonl"
+    }
+  },
+  "repo_split_balanced": {
+    "train": {
+      "rows": 20,
+      "file": "repo_split_balanced_train_first_20.jsonl"
+    },
+    "validation": {
+      "rows": 20,
+      "file": "repo_split_balanced_validation_first_20.jsonl"
+    },
+    "test": {
+      "rows": 20,
+      "file": "repo_split_balanced_test_first_20.jsonl"
+    }
+  }
+}