README install snippet is wrong: namespace, class name and composer name #3

From the SDK review 2026-09-15 — this breaks the PHP onboarding path.

Evidence: the README (same text block in all 4 repos) claims:

$cfg = GoAdServer\Api\Configuration::getDefaultConfiguration()->...
$api = new GoAdServer\Api\Api\AccountAPIApi(null, $cfg);
composer require goadserver/sdk:dev-main

Reality in this repo: the namespace is GoAdServerApi (lib/Configuration.php), the class is AccountApi (lib/Api/AccountApi.php), and the composer name is goadserver/goadserver-php (composer.json). Following the README gives Class not found.

Fix: correct the snippet to GoAdServerApi\Configuration / GoAdServerApi\Api\AccountApi / composer require goadserver/goadserver-php, and cover the README snippets with the round-trip smoke tests from clients/_smoke/ in the platform repo.