update docs

Signed-off-by: Jorge Turrado <jorge.turrado@mail.schwarz>

Author: JorTurFer

docs/resources/service_account_federated_identity_provider.md

@@ -68,7 +68,40 @@ resource "stackit_service_account_federated_identity_provider" "provider" {
 
 ```
 
+## Example Usage
+
+```terraform
+resource "stackit_service_account" "sa" {
+  project_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  name       = "my-service-account"
+}
+
+resource "stackit_service_account_federated_identity_provider" "provider" {
+  project_id            = stackit_service_account.sa.project_id
+  service_account_email = stackit_service_account.sa.email
+  name                  = "gh-actions"
+  issuer                = "https://token.actions.githubusercontent.com"
+
+  assertions = [
+    {
+      item     = "aud"
+      operator = "equals"
+      value    = "sts.accounts.stackit.cloud"
+    }
+    {
+      item     = "sub"
+      operator = "equals"
+      value    = "repo:stackitcloud/terraform-provider-stackit:ref:refs/heads/main"
+    }
+  ]
+}
 
+# Only use the import statement, if you want to import an existing federated identity provider
+import {
+  to = stackit_service_account_federated_identity_provider.import-example
+  id = "${var.project_id},${var.service_account_email},${var.federation_id}"
+}
+```
 
 <!-- schema generated by tfplugindocs -->
 ## Schema