Need documentation about environment variables introduced by CLOUD-1479.

Need to add descriptions about all the new environment variables introduced by CLOUD-1479 (*1) into the document of EAP 7.1 for OpenShift (*2).

(*1) CLOUD-1479 - Use common java defaults for xpaas images
https://issues.jboss.org/browse/CLOUD-1479

(*2) Red Hat JBoss Enterprise Application Platform > 7.1 > Red Hat JBoss Enterprise Application Platform for OpenShift
https://access.redhat.com/documentation/en-us/red_hat_jboss_enterprise_application_platform/7.1/html-single/red_hat_jboss_enterprise_application_platform_for_openshift/