Update README.md

Signed-off-by: fulleni <fulleni@hotmail.com>

Author: fulleni

README.md

@@ -4,6 +4,8 @@
 [![style: very good analysis](https://img.shields.io/badge/style-very_good_analysis-B22C89.svg)](https://pub.dev/packages/very_good_analysis) 
 [![License: PolyForm Free Trial](https://img.shields.io/badge/License-PolyForm%20Free%20Trial-blue)](https://polyformproject.org/licenses/free-trial/1.0.0)
 
+> **Note:** This package is being archived. Please use the successor package [`ht-data-repository`](https://github.com/headlines-toolkit/ht-data-repository) instead.
+
 Repository for managing user preferences. This repository acts as an intermediary between the application's business logic (BLoCs) and the data source client (`HtPreferencesClient`). It handles potential client-level exceptions and enforces additional business rules, such as limiting the size of the headline reading history.
 
 ## Overview