Added Disclaimer for Time Units

README.md

@@ -6535,6 +6535,9 @@ The corresponding labels for each event type can be read from metadata like this
 >>> [label for label in enumerate(meta_data.info.features["type_event"].feature.names)]
 ```
 
+Note: 
+The time unit of `time_since_last_event` for each dataset is 1 hour, except for Volcano (1_000_000 seconds), Taobao (10_000 seconds), Hawkes (undefined), Amazon (N/A), and Retweets (seconds)
+
 ### Data Splits
 
 |                   |  train|validation|  test|