JAVA-2751: Fix incorrect use of MongoClient constructor in async documentation.

Author: jyemin

docs/reference/content/driver-async/getting-started/quick-start-pojo.md

@@ -151,7 +151,8 @@ There are multiple ways to set the `pojoCodecRegistry` for use:
  - You can set it when instantiating a MongoClient object:
 
  ```java
- MongoClient mongoClient = new MongoClient("localhost", MongoClientOptions.builder().codecRegistry(pojoCodecRegistry).build());
+ MongoClient mongoClient = MongoClients.create(MongoClientSettings.builder()
+                                           .codecRegistry(pojoCodecRegistry).build());
 ```
 
 - You can use an alternative `CodecRegistry` with a `MongoDatabase`: