Code from section "22.6.12. Native REST client for Execution Server" is outdated

Since Drools/jBPM 6.3 we have a new Kie Server rest and Java APIs the section `22.6.12. Native REST client for Execution Server` in documentation still shows a sample for the old client. The correct code can be found at section `22.9. Kie Server Java Client API`. In this case, I think we can simply remove the `22.6.12. Native REST client for Execution Server` section:

https://docs.jboss.org/drools/release/7.0.0.Beta5/drools-docs/html_single/#_native_rest_client_for_execution_server