Documents changes in laravel/sanctum#564 (#10350)

* Documents changes in laravel/sanctum#564

Adds documentation to the Sanctum helper functions.

* Update sanctum.md

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Co-authored-by: Taylor Otwell <taylor@laravel.com>

Author: denjaland

sanctum.md

@@ -280,6 +280,8 @@ For this feature, Sanctum does not use tokens of any kind. Instead, Sanctum uses
 
 First, you should configure which domains your SPA will be making requests from. You may configure these domains using the `stateful` configuration option in your `sanctum` configuration file. This configuration setting determines which domains will maintain "stateful" authentication using Laravel session cookies when making requests to your API.
 
+To assist you in setting up your first-party stateful domains, Sanctum provides two helper functions that you can include in the configuration. First, `Sanctum::currentApplicationUrlWithPort()` will return the current application URL from the `APP_URL` environment variable, and `Sanctum::currentRequestHost()` will inject a placeholder into the stateful domain list which, at runtime, will be replaced by the host from the current request so that all requests with the same domain are considered stateful.
+
 > [!WARNING]
 > If you are accessing your application via a URL that includes a port (`127.0.0.1:8000`), you should ensure that you include the port number with the domain.