docs: fix example in README (#2717)

This is a tiny documentation fix to use `prefix` rather than `environment`, per the changes in #1858.

Author: ktheory

Diff for: README.md

@@ -167,7 +167,7 @@ module "github-runner" {
   vpc_id     = "vpc-123"
   subnet_ids = ["subnet-123", "subnet-456"]
 
-  environment = "gh-ci"
+  prefix = "gh-ci"
 
   github_app = {
     key_base64     = "base64string"
@@ -439,7 +439,7 @@ We welcome any improvement to the standard module to make the default as secure
 | <a name="input_enable_ssm_on_runners"></a> [enable\_ssm\_on\_runners](#input\_enable\_ssm\_on\_runners) | Enable to allow access the runner instances for debugging purposes via SSM. Note that this adds additional permissions to the runner instances. | `bool` | `false` | no |
 | <a name="input_enable_user_data_debug_logging_runner"></a> [enable\_user\_data\_debug\_logging\_runner](#input\_enable\_user\_data\_debug\_logging\_runner) | Option to enable debug logging for user-data, this logs all secrets as well. | `bool` | `false` | no |
 | <a name="input_enabled_userdata"></a> [enabled\_userdata](#input\_enabled\_userdata) | Should the userdata script be enabled for the runner. Set this to false if you are using your own prebuilt AMI. | `bool` | `true` | no |
-| <a name="input_environment"></a> [environment](#input\_environment) | A name that identifies the environment, used as prefix and for tagging. | `string` | `null` | no |
+| <a name="input_environment"></a> [environment](#input\_environment) | DEPRECATED, no longer used. See `prefix` | `string` | `null` | no |
 | <a name="input_fifo_build_queue"></a> [fifo\_build\_queue](#input\_fifo\_build\_queue) | Enable a FIFO queue to remain the order of events received by the webhook. Suggest to set to true for repo level runners. | `bool` | `false` | no |
 | <a name="input_ghes_ssl_verify"></a> [ghes\_ssl\_verify](#input\_ghes\_ssl\_verify) | GitHub Enterprise SSL verification. Set to 'false' when custom certificate (chains) is used for GitHub Enterprise Server (insecure). | `bool` | `true` | no |
 | <a name="input_ghes_url"></a> [ghes\_url](#input\_ghes\_url) | GitHub Enterprise Server URL. Example: https://github.internal.co - DO NOT SET IF USING PUBLIC GITHUB | `string` | `null` | no |

Diff for: variables.tf

@@ -20,7 +20,7 @@ variable "tags" {
 }
 
 variable "environment" {
-  description = "A name that identifies the environment, used as prefix and for tagging."
+  description = "DEPRECATED, no longer used. See `prefix`"
   type        = string
   default     = null