Add guest tools guide for FreeBSD

pages/02.linux/xcp-ng/xen-orchestra/default.en.md

@@ -112,3 +112,30 @@ To exclude disks from backup jobs, one can prepend the disk name with `[NOBAK]`
 ### Remove stale backups
 
 > [Backup list has a stale entry - how do I remove it?](https://xcp-ng.org/forum/topic/6462/backup-list-has-a-stale-entry-how-do-i-remove-it/2)
+
+## Xen Guest Tools
+
+### FreeBSD
+
+[shroot]
+
+```sh
+pkg install xen-guest-tools xe-guest-utilities
+```
+
+[/shroot]
+
+Start the agent  
+[shroot]
+
+```sh
+
+```
+
+[/shroot]
+
+To make sure the service is run on every boot, put this line into `/etc/rc.conf`:
+
+```
+xenguest_enable=YES
+```