Align os_disk_type description from azurerm provider

Signed-off-by: Mihai A <mihai.anei@gmail.com>

Author: lebenitza

variables.tf

@@ -93,7 +93,7 @@ variable "os_disk_size_gb" {
 }
 
 variable "os_disk_type" {
-  description = "The type of disk which should be used for the Operating System. Possible values are Ephemeral and Managed. Defaults to Managed. Changing this forces a new resource to be created."
+  description = "The type of disk which should be used for the Operating System. Possible values are `Ephemeral` and `Managed`. Defaults to `Managed`. Changing this forces a new resource to be created."
   type        = string
   default     = "Managed"
 }