Include a template comment that provider metadata can be used to set module_name

[displague]

Include a template comment that provider metadata can be used to set module_name

https://developer.hashicorp.com/terraform/internals/provider-meta

terraform {
  provider_meta "equinix" {
#   TEMPLATE: Set the name of the module below 
#    module_name = "example"
  }
}

Relates to equinix/terraform-provider-equinix#252