Update README.md

README.md

@@ -12,9 +12,7 @@ NOTE:
  
   - In the last dialogue turn is always the system that greets the user; this last turn is kept and the user utterance is filled in with the `none` string (usually during evaluation this dialogue turn is not considered)
   
-  - To be able to save data as an arrow file you need to "pad" the states to all have the same keys. To do this the None value is introduced. Therefore, when you load it back it is convenient to have a way to remove the "padding".
-  
-  In order to do so, a function like the following can help
+  - To be able to save data as an arrow file you need to "pad" the states to all have the same keys. To do this the None value is introduced. Therefore, when you load it back it is convenient to have a way to remove the "padding". In order to do so, a function like the following can help
   
   ```python 
   def remove_empty_slots(state: Union[Dict[str, Union[List[str], None]], None]) -> Union[Dict[str, List[str]], None]:
@@ -23,4 +21,39 @@ NOTE:
         return None
 
     return {k: v for k, v in state.items() if v is not None}
-  ```
+  ```
+  
+  - The schema has been updated to make all the versions compatible. Basically, the "book" string has been removed from slots in v2.2. The updated schema is the following
+  
+```yaml
+attraction-area
+attraction-name
+attraction-type
+hotel-area
+hotel-day
+hotel-internet
+hotel-name
+hotel-parking
+hotel-people
+hotel-pricerange
+hotel-stars
+hotel-stay
+hotel-type
+restaurant-area
+restaurant-day
+restaurant-food
+restaurant-name
+restaurant-people
+restaurant-pricerange
+restaurant-time
+taxi-arriveby
+taxi-departure
+taxi-destination
+taxi-leaveat
+train-arriveby
+train-day
+train-departure
+train-destination
+train-leaveat
+train-people
+```