Add blurp about experimental 8.4 support. (#1860)

Signed-off-by: Dirkjan Bussink <[email protected]>

content/en/docs/21.0/overview/supported-databases.md

@@ -16,12 +16,17 @@ Vitess supports the core features of MySQL 8.0.\*,
 with [some limitations](../../reference/compatibility/mysql-compatibility/). Vitess also
 supports [Percona Server for MySQL](https://www.percona.com/software/mysql-database/percona-server) 8.0.\*.
 
+### Experimental MySQL 8.4 support
+
+Vitess has experimental MySQL 8.4 support with
+[the same limitations](../../reference/compatibility/mysql-compatibility/) as 8.0.\*.
+
 ## Supported Databases For Imports
 
 Vitess supports importing from a wide range of databases that include: 
 
-- [MySQL](https://www.mysql.com/) version 5.7 to 8.0
-- [Percona Server for MySQL](https://www.percona.com/software/mysql-database/percona-server) version 5.7 to 8.0
+- [MySQL](https://www.mysql.com/) version 5.7 to 8.0. Experimental support for 8.4.
+- [Percona Server for MySQL](https://www.percona.com/software/mysql-database/percona-server) version 5.7 to 8.0. Experimental support for 8.4.
 - [MariaDB](https://mariadb.com) versions 10.10+
 
 ## See also