docs(cost-centers): add usage example

Add example Terraform configuration demonstrating how to:
- Create a cost center
- Assign users, organizations, and repositories
- Use data sources to query cost centers

Author: github-actions[bot]

examples/cost_centers/main.tf

@@ -0,0 +1,115 @@
+terraform {
+  required_providers {
+    github = {
+      source  = "integrations/github"
+      version = "~> 6.11"
+    }
+  }
+}
+
+provider "github" {
+  token = var.github_token
+  owner = var.enterprise_slug
+}
+
+variable "github_token" {
+  description = "GitHub classic personal access token (PAT) for an enterprise admin"
+  type        = string
+  sensitive   = true
+}
+
+variable "enterprise_slug" {
+  description = "The GitHub Enterprise slug"
+  type        = string
+}
+
+variable "cost_center_name" {
+  description = "Name for the cost center"
+  type        = string
+}
+
+variable "users" {
+  description = "Usernames to assign to the cost center"
+  type        = list(string)
+  default     = []
+}
+
+variable "organizations" {
+  description = "Organization logins to assign to the cost center"
+  type        = list(string)
+  default     = []
+}
+
+variable "repositories" {
+  description = "Repositories (full name, e.g. org/repo) to assign to the cost center"
+  type        = list(string)
+  default     = []
+}
+
+# The cost center resource manages only the cost center entity itself.
+resource "github_enterprise_cost_center" "example" {
+  enterprise_slug = var.enterprise_slug
+  name            = var.cost_center_name
+}
+
+# Use separate authoritative resources for assignments.
+# These are optional - only create them if you have items to assign.
+
+resource "github_enterprise_cost_center_users" "example" {
+  count = length(var.users) > 0 ? 1 : 0
+
+  enterprise_slug = var.enterprise_slug
+  cost_center_id  = github_enterprise_cost_center.example.id
+  usernames       = var.users
+}
+
+resource "github_enterprise_cost_center_organizations" "example" {
+  count = length(var.organizations) > 0 ? 1 : 0
+
+  enterprise_slug     = var.enterprise_slug
+  cost_center_id      = github_enterprise_cost_center.example.id
+  organization_logins = var.organizations
+}
+
+resource "github_enterprise_cost_center_repositories" "example" {
+  count = length(var.repositories) > 0 ? 1 : 0
+
+  enterprise_slug  = var.enterprise_slug
+  cost_center_id   = github_enterprise_cost_center.example.id
+  repository_names = var.repositories
+}
+
+# Data sources for reading cost center information
+data "github_enterprise_cost_center" "by_id" {
+  enterprise_slug = var.enterprise_slug
+  cost_center_id  = github_enterprise_cost_center.example.id
+}
+
+data "github_enterprise_cost_centers" "active" {
+  enterprise_slug = var.enterprise_slug
+  state           = "active"
+
+  depends_on = [github_enterprise_cost_center.example]
+}
+
+output "cost_center" {
+  description = "Created cost center"
+  value = {
+    id                 = github_enterprise_cost_center.example.id
+    name               = github_enterprise_cost_center.example.name
+    state              = github_enterprise_cost_center.example.state
+    azure_subscription = github_enterprise_cost_center.example.azure_subscription
+  }
+}
+
+output "cost_center_from_data_source" {
+  description = "Cost center fetched by data source (includes all assignments)"
+  value = {
+    id            = data.github_enterprise_cost_center.by_id.cost_center_id
+    name          = data.github_enterprise_cost_center.by_id.name
+    state         = data.github_enterprise_cost_center.by_id.state
+    users         = sort(tolist(data.github_enterprise_cost_center.by_id.users))
+    organizations = sort(tolist(data.github_enterprise_cost_center.by_id.organizations))
+    repositories  = sort(tolist(data.github_enterprise_cost_center.by_id.repositories))
+  }
+}