Proposing fixes for contrib/terraform/vsphere/ #8436 (#8441)

* fixes issues in vSphere Terraform contrib. #8436

* fix formatting

* add variables to the main module and document changes

* add missing newline

contrib/terraform/vsphere/modules/kubernetes-cluster/templates/metadata.tpl

@@ -0,0 +1,14 @@
+instance-id: ${hostname}
+local-hostname: ${hostname}
+network:
+  version: 2
+  ethernets:
+    ${interface_name}:
+      match:
+        name: ${interface_name}
+      dhcp4: false
+      addresses:
+        - ${ip}/${netmask}
+      gateway4: ${gw}
+      nameservers:
+        addresses: [${dns}]