Improve README

README.md

@@ -53,7 +53,7 @@ It also has several optional arguments:
 
 `featurize_model_name`: name of the model from which features are obtained, from one of the following: `gpt2`, `gpt2-medium`, `gpt2-large`, `gpt2-xl`. The default is `gpt2-large`.
 
-`device_id`: Device for featurization. Supply a GPU id (e.g. `0` or `3`) to use GPU. If no GPU with this id is found, the metric will use CPU.
+`device_id`: Device for featurization. Supply a GPU id (int) (e.g. `0` or `3`) to use GPU. If no GPU with this id is found, the metric will use CPU.
 
 `max_text_length`: maximum number of tokens to consider. The default is `1024`.