Merge pull request #227 from Adyen/readme-update

Update README file

README.md

@@ -3,6 +3,13 @@ Use Adyen's plugin for Shopware 5 to offer frictionless payments online, in-app,
 
 **Note**: if you are still using an **older version** of the Adyen Shopware 5 integration (**below v4.0**) please refer to [this documentation](https://github.com/Adyen/adyen-shopware5/wiki/Home/2b286ac3ae0a3ddf9dcba1f6fb13e69e0f6d2602).
 
+#### Important information ####
+Support deprecation plan for old plugins Shopware5 (below major release v4.0):
+1. Only critical functionality and security updates until June 2024.
+   Note: the Shopware5 platform will also be [sunset](https://www.shopware.com/en/news/shopware-5-how-it-continues/) from July 2024 onwards.
+2. Only critical security updates from June 2024 until June 2025.
+3. Support will be fully suspended for old Prestashop and Shopware5 plugins from June 2025 onwards.
+
 ## Contributing
 We strongly encourage you to join us in contributing to this repository so everyone can benefit from:
 * New features and functionality