Fix doc

Author: bakura10

docs/07. Cookbook.md

@@ -296,7 +296,7 @@ request per each resource: /customers/1, /customers/2, /customers/5... However t
 of requests and roundtrip to your server.
 
 Instead, ZfrRest allows you to enable "coalesce filtering" for identifier. This allows you to do a request like that:
-/customers?ids[]=2&ids[]=3&ids[]=5... and ZfrRest will automatically returns you the filtered collection.
+/customers?ids[]=2&$ids[]=3&$ids[]=5... and ZfrRest will automatically returns you the filtered collection.
 
 This feature is disabled by default, and you can enable it using the `enable_coalesce_filtering`. You can also customize
 the query key using the `coalesce_filtering_query_key` option (default to "$ids"):