title: create an azure resource group under a subscription with terraform
body: <p>I am looking at this example from the terraform docs for creating an azure group:</p>
  
  <pre><code>resource "azurerm_resource_group" "test" {
    name     = "testResourceGroup1"
    location = "West US"
  
    tags = {
      environment = "Production"
    }
  }
  </code></pre>
  
  <p>It does not specify the subscription anywhere.</p>
  
  <p>How can I specify the subscription?</p>