HZX-1138: removed broken link (#1334)

Removed a line which links to an example that no longer exists

docs/modules/mapstore/pages/implement-a-mapstore.adoc

@@ -33,8 +33,6 @@ TIP: By default, MapStores are loaded as soon as the first cluster member starts
 
 The `destroy()` method is called during the graceful shutdown of a Hazelcast member. You can override this method to clean up the resources held by the MapStore, such as closing the database connections.
 
-See an https://github.com/hazelcast/hazelcast-code-samples/blob/master/hazelcast-integration/mongodb/src/main/java/com/hazelcast/loader/MongoMapStore.java[example of this interface].
-
 [[configuring-a-connection-using-properties]]
 
 You can declaratively specify the database properties in your configuration file and then implement the `init()` method to receive those properties. For example, you can define the database URL and name, using the `properties` configuration element. The following is a configuration example for MongoDB: