Add README.

README.md

@@ -13,6 +13,27 @@ The model weights are released by Google DeepMind.
 
 The model weights are made available for use under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0). You may obtain a copy of the License at: https://creativecommons.org/licenses/by-nc-sa/4.0/.
 
+## Usage
+
+You can load the model like so:
+
+```python
+from graphcast import checkpoint
+
+REPO_ID = "shermansiu/dm_graphcast"
+FILENAME = ""
+
+with open(hf_hub_download(repo_id=REPO_ID, filename=FILENAME), "rb") as f:
+    ckpt = checkpoint.load(f, graphcast.CheckPoint)
+params = ckpt.params
+state = {}
+
+model_config = ckpt.model_config
+task_config = ckpt.task_config
+```
+
+For more details, check out https://github.com/shermansiu/graphcast/blob/main/graphcast_demo_hf.ipynb
+
 ## Citation
 - Paper: https://www.science.org/doi/10.1126/science.adi2336
 - Preprint: https://arxiv.org/abs/2212.12794