Fix the tag in the SageMaker notebook link

The link pins the notebook to tag 2.2.2, and the repository tags that release as v2.2.2, so it returns 404. The pinned version is kept and only the tag gains its prefix. The notebook path is unchanged and the URL returns 200.

README.md

@@ -155,7 +155,7 @@ payload = {
 forecast = predictor.predict(payload)["predictions"]
 ```
 
-For more details about the endpoint API, check out the [example notebook](https://github.com/amazon-science/chronos-forecasting/blob/2.2.2/notebooks/deploy-chronos-to-amazon-sagemaker.ipynb).
+For more details about the endpoint API, check out the [example notebook](https://github.com/amazon-science/chronos-forecasting/blob/v2.2.2/notebooks/deploy-chronos-to-amazon-sagemaker.ipynb).
 
 
 ## Training data