docs: add note for java client CP pom (#5894)

docs/developer-guide/ksqldb-clients/java-client.md

@@ -103,6 +103,12 @@ Start by creating a `pom.xml` for your Java application:
 </project>
 ```
 
+!!! note
+      If you’re using ksqlDB for Confluent Platform (CP), use the CP-specific modules
+      from [http://packages.confluent.io/maven/](http://packages.confluent.io/maven/)
+      by replacing the repositories in the example POM above with a repository with this
+      URL instead. Also update `ksqldb.version` to be a CP version, such as `6.0.0`, instead.
+
 Create your example app at `src/main/java/my/ksqldb/app/ExampleApp.java`:
 
 ```java
@@ -124,6 +130,7 @@ public class ExampleApp {
 
     // Send requests with the client by following the other examples
 
+    // Terminate any open connections and close the client
     client.close();
   }
 }