Updated changelog and readme.

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CKEditor 4 Angular Integration Changelog
 
+⚠️️️ **CKEditor 4 (the open source edition) is no longer maintained.** ⚠️
+
+If you would like to keep access to future CKEditor 4 security patches, check the [Extended Support Model](https://ckeditor.com/ckeditor-4-support/), which guarantees **security updates and critical bug fixes until December 2026**. Alternatively, [upgrade to CKEditor 5](https://ckeditor.com/docs/ckeditor5/latest/updating/ckeditor4/migration-from-ckeditor-4.html).
+
 ## ckeditor4-angular 4.0.0
 
 BREAKING CHANGES:

README.md

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 [![Join newsletter](https://img.shields.io/badge/join-newsletter-00cc99.svg)](http://eepurl.com/c3zRPr)
 [![Follow Twitter](https://img.shields.io/badge/follow-twitter-00cc99.svg)](https://twitter.com/ckeditor)
 
+## ⚠️ CKEditor 4: End of Life and Extended Support Model until Dec 2026
+
+CKEditor 4 was launched in 2012 and reached its End of Life (EOL) on June 30, 2023.
+
+A special edition, **[CKEditor 4 LTS](https://ckeditor.com/ckeditor-4-support/)** ("Long Term Support"), is available under commercial terms (["Extended Support Model"](https://ckeditor.com/ckeditor-4-support/)) for anyone looking to **extend the coverage of security updates and critical bug fixes**.
+
+With CKEditor 4 LTS, security updates and critical bug fixes are guaranteed until December 2026.
+
+## About this package
+
 Official [CKEditor 4](https://ckeditor.com/ckeditor-4/) WYSIWYG editor component for Angular.
 
 We are looking forward to your feedback! You can report any issues, ideas or feature requests on the [integration issues page](https://github.com/ckeditor/ckeditor4-angular/issues/new).