add deprecation notice

Author: edodusi

README.md

@@ -1,8 +1,12 @@
+> [!WARNING]  
+> This package is discontinued and will only receive critical security updates.\
+> Please use the new official [PHP Content API Client](https://github.com/storyblok/php-content-api-client).
+
 <div style="text-align:center">
 	<a  href="https://www.storyblok.com?utm_source=github.com&utm_medium=readme&utm_campaign=php-client"  align="center">
 		<img  src="https://a.storyblok.com/f/88751/1776x360/dc6e51a5fd/sb-php.png"  alt="Storyblok Logo">
 	</a>
-	<h1  style="text-align:center">Storyblok PHP Client</h1>
+	<h1  style="text-align:center">Storyblok PHP Client - Deprecated</h1>
 	<p  style="text-align:center">This is the official <a href="https://www.storyblok.com?utm_source=github.com&utm_medium=referral&utm_campaign=php-client">Storyblok</a> PHP client to easily access the Content Delivery API and Management API.</p>
 </div>