README.md in disco-0.2.7 vs README.md in disco-0.2.8

@@ -42,10 +42,12 @@
   {user_id: 1, item_id: 1},
   {user_id: 2, item_id: 1}
 ])
 ```
 
+> Each `user_id`/`item_id` combination should only appear once
+
 Get user-based recommendations - “users like you also liked”
 
 ```ruby
 recommender.user_recs(user_id)
 ```
@@ -95,14 +97,10 @@
 ### Ahoy
 
 [Ahoy](https://github.com/ankane/ahoy) is a great source for implicit feedback
 
 ```ruby
-views = Ahoy::Event.
-  where(name: "Viewed post").
-  group(:user_id).
-  group("properties->>'post_id'"). # postgres syntax
-  count
+views = Ahoy::Event.where(name: "Viewed post").group(:user_id).group_prop(:post_id).count
 
 data =
   views.map do |(user_id, post_id), _|
     {
       user_id: user_id,