added terraform for create a virtual network with two subnets quickstart in virtual network docset

quickstart/101-virtual-network-create-two-subnets/variables.tf

@@ -0,0 +1,17 @@
+variable "resource_group_location" {
+  type        = string
+  default     = "eastus"
+  description = "Location of the resource group."
+}
+
+variable "prefix" {
+  type        = string
+  default     = "rg"
+  description = "Prefix of the resource group name that's combined with a random ID so name is unique in your Azure subscription."
+}
+
+variable "vnet_address_space" {
+  type        = list(string)
+  default     = ["10.0.0.0/16"]
+  description = "Address space for the virtual network."
+}