README.md in disco-0.3.0 vs README.md in disco-0.3.1

@@ -181,20 +181,22 @@
 ## Storing Recommenders
 
 If you’d prefer to perform recommendations on-the-fly, store the recommender
 
 ```ruby
-bin = Marshal.dump(recommender)
-File.binwrite("recommender.bin", bin)
+json = recommender.to_json
+File.write("recommender.json", json)
 ```
 
-> You can save it to a file, database, or any other storage system
+> You can save it to a file, database, or any other storage system. Also, user and item IDs should be integers or strings for this.
 
+The serialized recommender includes user activity from the training data (to avoid recommending previously rated items), so be sure to protect it.
+
 Load a recommender
 
 ```ruby
-bin = File.binread("recommender.bin")
-recommender = Marshal.load(bin)
+json = File.read("recommender.json")
+recommender = Disco::Recommender.load_json(json)
 ```
 
 Alternatively, you can store only the factors and use a library like [Neighbor](https://github.com/ankane/neighbor). See the [examples](https://github.com/ankane/neighbor/tree/master/examples).
 
 ## Algorithms