Updated Front Door Classic code sample (#244)

quickstart/101-front-door-classic/variables.tf

@@ -1,15 +1,17 @@
-variable "location" {
-  type    = string
-  default = "westus2"
+variable "resource_group_location" {
+  type        = string
+  description = "Location for all resources."
+  default     = "eastus"
+}
+
+variable "resource_group_name_prefix" {
+  type        = string
+  description = "Prefix of the resource group name that's combined with a random ID so name is unique in your Azure subscription."
+  default     = "rg"
 }
 
 variable "backend_address" {
-  default = "www.bing.com"
   type    = string
-}
-
-variable "prefix" {
-  type        = string
-  default     = "front-door-classic"
-  description = "Prefix of the resource name"
+  description = "Backend address."
+  default = "www.bing.com"
 }