Add missing import

README.md

@@ -19,6 +19,7 @@ You can load the model like so:
 
 ```python
 from graphcast import checkpoint
+from huggingface_hub import hf_hub_download
 
 REPO_ID = "shermansiu/dm_graphcast"
 FILENAME = "GraphCast - ERA5 1979-2017 - resolution 0.25 - pressure levels 37 - mesh 2to6 - precipitation input and output.npz"