hardware-and-software-requirements: Add note about supported filesystems

Author: dveeden

hardware-and-software-requirements.md

@@ -225,7 +225,7 @@ As an open-source distributed SQL database, TiDB requires the following network
 | Alertmanager | 9093 | the port for the alert web service |
 | Alertmanager | 9094 | the alert communication port |
 
-## Disk space requirements
+## Storage requirements
 
 <table>
 <thead>
@@ -269,6 +269,8 @@ As an open-source distributed SQL database, TiDB requires the following network
 </tbody>
 </table>
 
+TiDB supports XFS and Ext4 filesystems, other filesystems are not tested.
+
 ## Web browser requirements
 
 TiDB relies on [Grafana](https://grafana.com/) to provide visualization of database metrics. A recent version of Microsoft Edge, Safari, Chrome or Firefox with Javascript enabled is sufficient.