document how to disable AFS

admin-guide/configuration/mount.md

@@ -123,6 +123,23 @@ Following details can be modified, but are usually not required:
 - `afs_client::files`
 - `afs_client::dcache`
 
+When disabling AFS the daemon is not automatically switched off. There is additional manual effort required on the host:
+
+```
+systemctl disable yfs-client.service
+reboot
+```
+
+If you want to do it without reboot, first stop all processes using AFS. You might figure them out e.g. with `lsof | grep /afs`.
+
+Then do
+```
+umount /afs
+systemctl stop yfs-client.service
+systemctl disable yfs-client.service
+afsd -shutdown
+```
+
 
 ## Bind Mounts
 Bind mounts can be defined as follows: