chore: update basic example (#70)

Author: iamar7

examples/basic/main.tf

@@ -24,5 +24,5 @@ module "cloud_monitoring" {
   region            = var.region
   resource_tags     = var.resource_tags
   instance_name     = local.cloud_monitoring_instance_name
-  plan              = var.plan
+  plan              = "graduated-tier"
 }

examples/basic/variables.tf

@@ -37,9 +37,3 @@ variable "resource_tags" {
   description = "List of resource tag to associate with all resource instances created by this example."
   default     = []
 }
-
-variable "plan" {
-  type        = string
-  description = "The IBM Cloud Monitoring plan to provision. Available: lite, graduated-tier and graduated-tier-sysdig-secure-plus-monitor (available in region eu-fr2 only)"
-  default     = "graduated-tier"
-}