Version bump, Style guide, dns records updates optional, and input validation

variable.region.tf

@@ -1,4 +1,10 @@
 variable "region" {
-  default = "us-central"
-  type    = string
+  default     = "us-central"
+  description = "The region where the Linode will be located."
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-z]{2}-[a-z]+(-[a-z]+)?$", var.region))
+    error_message = "The region must be a valid Linode region format (e.g., us-central, ap-south)."
+  }
 }