added nb3 dataset Builder

ark_example.py

@@ -112,6 +112,11 @@ class ArkExample(datasets.GeneratorBasedBuilder):
             description="This dataset is a superset of the nb1 and contains data from notebook 1 in order to start with notebook 2. \
                 Therefore you can start at any notebook with this dataset.",
         ),
+        datasets.BuilderConfig(
+            name="nb3",
+            version=VERSION,
+            description="This dataset contains pixel data generated from Notebook 2 in the Pixie pipeline."
+        )
     ]
 
     def _info(self):