improve some docs

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

examples/backup/README.md

@@ -1,5 +1,7 @@
 # Data Backup
 
+:warning: Since v2.4.0 you can use the [EventManager](../../docs/eventmanager.md) to schedule backups.
+
 The `backup` example script shows how to use the SFTPGo REST API to backup your data.
 
 The script is written in Python and has the following requirements:

examples/data-retention/README.md

@@ -1,5 +1,7 @@
 # File retention policies
 
+:warning: Since v2.4.0 you can use the [EventManager](../../docs/eventmanager.md) to schedule data retention checks.
+
 The `checkretention` example script shows how to use the SFTPGo REST API to manage data retention.
 
 :warning: Deleting files is an irreversible action, please make sure you fully understand what you are doing before using this feature, you may have users with overlapping home directories or virtual folders shared between multiple users, it is relatively easy to inadvertently delete files you need.

examples/quotascan/README.md

@@ -1,5 +1,7 @@
 # Update user quota
 
+:warning: Since v2.4.0 you can use the [EventManager](../../docs/eventmanager.md) to schedule quota scans.
+
 The `scanuserquota` example script shows how to use the SFTPGo REST API to update the users' quota.
 
 The stored quota may be incorrect for several reasons, such as an unexpected shutdown while uploading files, temporary provider failures, files copied outside of SFTPGo, and so on.

fail2ban/README.md

@@ -0,0 +1,3 @@
+# Fail2ban
+
+:warning: We recommend using the [built-in defender](../docs/defender.md) instead of Fail2ban.