Add the prerequiesit for JAVA_HOME in wdt

Author: CarolynRountree

kubernetes/samples/scripts/create-weblogic-domain/domain-home-in-image/README.md

@@ -5,6 +5,7 @@ The sample scripts demonstrate the creation of a WebLogic domain home in a Docke
 ## Prerequisites
 
 The following prerequisites must be handled prior to running the create domain script:
+* The WDT sample requires that JAVA_HOME is set to a java JDK version 1.8 or greater
 * Make sure the WebLogic operator is running.
 * The operator requires WebLogic Server 12.2.1.3.0 with patch 28076014 applied. Refer to [Weblogic Docker images](../../../../../site/weblogic-docker-images.md) for details on how to create one. If a different `domainHomeImageBase` (see Configuration table below) is specified, the specified image needs to be built locally or pulled from a repository.
 * Create a Kubernetes namespace for the domain unless the intention is to use the default namespace.

kubernetes/samples/scripts/create-weblogic-domain/domain-home-in-image/create-domain.sh

@@ -9,6 +9,7 @@
 #  The domain creation inputs can be customized by editing create-domain-inputs.yaml
 #
 #  The following pre-requisites must be handled prior to running this script:
+#    * The WDT sample requires that JAVA_HOME is set to a java JDK version 1.8 or greater
 #    * The kubernetes namespace must already be created
 #    * The kubernetes secrets 'username' and 'password' of the admin account have been created in the namespace
 #