chore: update readme to add info about core implementation

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        version: [ "v6.6.1.1", "v6.6.0.3", "trunk" ]
+        version: [ "v6.6.3.1", "v6.6.2.0", "v6.6.1.1", "v6.6.0.3" ]
         php-version: [ "8.2" ]
     runs-on: ubuntu-latest
     steps:

README.md

@@ -2,6 +2,8 @@
 
 [![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE.md) [![Shopware Store](https://img.shields.io/badge/shopware-store-blue.svg?style=flat-square)](https://store.shopware.com/en/frosh69611263569f/thumbnailprocessor-plugin.html)
 
+> :warning: the function of this plugin will be in core with release of [this commit](https://github.com/shopware/shopware/commit/7c170d3fb0754ce9671bb00a0fd949a80fc74d96). Therefore, we will discontinue this plugin soon.
+
 This plugin allows you to use variable thumbnails, if your filesystem (or storage-adapter) supports it.
 So you [don't need modern file formats](https://blog.tinect.de/posts/you-might-not-need-thumbnails-or-modern-image-format/).  
 Besides the benefits for using it in live shops, you can use this also in development-systems, if you don't want thumbnails to be created.