[VOL-3780] using keywords in physical build

Change-Id: I6fbe3797f57920b5d8ebb2419c8c2ba6de9d0901
diff --git a/vars/volthaDeploy.groovy b/vars/volthaDeploy.groovy
index 29d090e..5b0adc3 100644
--- a/vars/volthaDeploy.groovy
+++ b/vars/volthaDeploy.groovy
@@ -17,6 +17,7 @@
       extraHelmFlags: "",
       localCharts: false, // wether to use locally cloned charts or upstream one (for local we assume they are stored in $WORKSPACE/voltha-helm-charts)
       dockerRegistry: "", // use a different docker registry for all images, eg: "mirror.registry.opennetworking.org"
+      kubeconfig: null, // location of the kubernetes config file, if null we assume it's stored in the $KUBECONFIG environment variable
     ]
 
     if (!config) {