docs(README.md): use the new variable scheduler_tag

In README.md, renames the terraform variable "resource_tag" with the new variable name: "scheduler_tag". "resource_tag" name will remain valid but will be deprecated.

Author: diodonfrost

README.md

@@ -31,7 +31,7 @@ module "stop_ec2_instance" {
  ec2_schedule = "true"
  rds_schedule = "false"
  cloudwatch_alarm_schedule = "false"
- resources_tag = {
+ scheduler_tag = {
  key = "tostop"
  value = "true"
  }
@@ -46,7 +46,7 @@ module "start_ec2_instance" {
  ec2_schedule = "true"
  rds_schedule = "false"
  cloudwatch_alarm_schedule = "false"
- resources_tag = {
+ scheduler_tag = {
  key = "tostop"
  value = "true"
  }