Improved warning message for Kubernetes secrets (#907)

* Fix validation error message for secrets

* more elaborate update

Author: jshum2479

core/src/main/resources/oracle/weblogic/deploy/messages/wlsdeploy_rb.properties

@@ -337,7 +337,10 @@ WLSDPLY-01735=Assignment in {0} is not formatted as X=Y: {1}
 WLSDPLY-01736=Default variable file name {0}
 WLSDPLY-01737=Environment variable "{0}" was not found
 WLSDPLY-01738=Path in {0} is not a directory: {1}
-WLSDPLY-01739=Error: Could not resolve secret token "{0}". Known secrets include: {1}
+WLSDPLY-01739=Could not resolve secret token "{0}". Known secrets include: {1}.  Secrets can only be resolved in \
+  Kubernetes environment. The secret token's name and keys must have a matching Kubernetes secret name and literals \
+  in the same namespace. For WebLogic Kubernetes Operator deployment, you must specify the secret name in \
+  "domain.spec.configuration.secrets"  
 
 # wlsdeploy/util/weblogic_helper.py
 WLSDPLY-01740=Encryption failed: Unable to locate SerializedSystemIni