Remove unstable warning

Author: thomascube

README.md

@@ -4,13 +4,6 @@ Roundcube Webmail
 
 [![Tests Status](https://github.com/roundcube/roundcubemail/actions/workflows/tests.yml/badge.svg?branch=master)](https://github.com/roundcube/roundcubemail/actions/workflows/tests.yml)
 
-ATTENTION
----------
-This is just a snapshot from the GIT repository and is **NOT A STABLE
-version of Roundcube**. It's not recommended to replace an existing installation
-of Roundcube with this version. Also using a separate database for this
-installation is highly recommended.
-
 
 INTRODUCTION
 ------------