chore(provider): mark deprecation for service_account_token (#920)

* chore(provider): make deprecation for service_account_token

---------

Signed-off-by: Mauritz Uphoff <mauritz.uphoff@stackit.cloud>
Co-authored-by: Ruben Hoenle <Ruben.Hoenle@stackit.cloud>

docs/index.md

@@ -11,7 +11,7 @@ provider "stackit" {
 
 # Authentication
 
-# Token flow
+# Token flow (scheduled for deprecation and will be removed on December 17, 2025)
 provider "stackit" {
   default_region        = "eu01"
   service_account_token = var.service_account_token
@@ -37,7 +37,7 @@ provider "stackit" {
 To authenticate, you will need a [service account](https://docs.stackit.cloud/stackit/en/service-accounts-134415819.html). Create it in the [STACKIT Portal](https://portal.stackit.cloud/) and assign it the necessary permissions, e.g. `project.owner`. There are multiple ways to authenticate:
 
 - Key flow (recommended)
-- Token flow
+- Token flow (is scheduled for deprecation and will be removed on December 17, 2025)
 
 When setting up authentication, the provider will always try to use the key flow first and search for credentials in several locations, following a specific order:
 
@@ -112,6 +112,8 @@ To configure the key flow, follow this steps:
 
 ### Token flow
 
+> Is scheduled for deprecation and will be removed on December 17, 2025.
+
 Using this flow is less secure since the token is long-lived. You can provide the token in several ways:
 
 1. Setting the field `service_account_token` in the provider
@@ -182,7 +184,7 @@ Note: AWS specific checks must be skipped as they do not work on STACKIT. For de
 - `service_account_email` (String, Deprecated) Service account email. It can also be set using the environment variable STACKIT_SERVICE_ACCOUNT_EMAIL. It is required if you want to use the resource manager project resource.
 - `service_account_key` (String) Service account key used for authentication. If set, the key flow will be used to authenticate all operations.
 - `service_account_key_path` (String) Path for the service account key used for authentication. If set, the key flow will be used to authenticate all operations.
-- `service_account_token` (String) Token used for authentication. If set, the token flow will be used to authenticate all operations.
+- `service_account_token` (String, Deprecated) Token used for authentication. If set, the token flow will be used to authenticate all operations.
 - `service_enablement_custom_endpoint` (String) Custom endpoint for the Service Enablement API
 - `ske_custom_endpoint` (String) Custom endpoint for the Kubernetes Engine (SKE) service
 - `sqlserverflex_custom_endpoint` (String) Custom endpoint for the SQL Server Flex service

docs/resources/service_account_access_token.md

@@ -4,6 +4,7 @@ page_title: "stackit_service_account_access_token Resource - stackit"
 subcategory: ""
 description: |-
   Service account access token schema.
+  !> This resource is scheduled for deprecation and will be removed on December 17, 2025. To ensure a smooth transition, please refer to our migration guide at https://docs.stackit.cloud/stackit/en/deprecation-plan-for-service-account-access-tokens-and-migration-guide-373293307.html for detailed instructions and recommendations.
   Example Usage
   Automatically rotate access tokens
   
@@ -30,6 +31,9 @@ description: |-
 # stackit_service_account_access_token (Resource)
 
 Service account access token schema.
+
+!> This resource is scheduled for deprecation and will be removed on December 17, 2025. To ensure a smooth transition, please refer to our migration guide at https://docs.stackit.cloud/stackit/en/deprecation-plan-for-service-account-access-tokens-and-migration-guide-373293307.html for detailed instructions and recommendations.
+
 ## Example Usage