Updated file naming per review

quickstart/101-resource-group/main.tf

@@ -1,8 +1,8 @@
-resource "random_pet" "rg-name" {
+resource "random_pet" "rg_name" {
   prefix    = var.resource_group_name_prefix
 }
 
 resource "azurerm_resource_group" "rg" {
-  name      = random_pet.rg-name.id
+  name      = random_pet.rg_name.id
   location  = var.resource_group_location
 }