docs: update dataset card with usage

README.md

@@ -27,6 +27,13 @@ configs:
 
 Source Paper: https://arxiv.org/abs/1802.06916
 
+### Usage
+```
+from torch_geometric.datasets.cornell import CornellTemporalHyperGraphDataset
+
+dataset = CornellTemporalHyperGraphDataset(root = "./", name="NDC-classes", split="train")
+```
+
 ### Citation
 
 ```misc