deprecated the plugin

Signed-off-by: Nicola Murino <[email protected]>

Author: drakkan

README.md

@@ -3,6 +3,8 @@
 ![Build](https://github.com/sftpgo/sftpgo-plugin-metadata/workflows/Build/badge.svg?branch=main&event=push)
 [![License: AGPL v3](https://img.shields.io/badge/License-AGPLv3-blue.svg)](https://www.gnu.org/licenses/agpl-3.0)
 
+:warning: This plugin is deprecated and will no longer work starting from SFTPGo 2.6.0.
+
 This plugin allows to store file metadata in supported database engines.
 
 ## Supported metadata