Update rename hostname documenation

admin-guide/configuration/basic/host_rename.md

@@ -10,12 +10,14 @@ For sysdb create a new node with bob as usual.
 For reference do
 
 ```
+OLD_FQDN=my-old-hostname.psi.ch
+NEW_FQDN=my-new-hostname.psi.ch
 bob node list -v $OLD_FQDN
 ```
 then add the new node
 ```
 bob node add $NEW_FQDN $SYSDB_ENV
-bod node set-attr $NEW_FQDN [all attributes as listed above]
+bob node set-attr $NEW_FQDN [all attributes as listed above]
 ```
 and the same for the MAC addresses:
 ```
@@ -42,6 +44,12 @@ which changes the local hostname, removes the local Puppet certificate and updat
 
 - change DNS entry if a static IP address is assigned
 - redo SSL/TLS certificates with new hostname
+- if the host is icinga2 monitored you need to remove icinga2 from the host before running puppet so that a new cert, etc. is generated for the host
+```
+yum remove icinga2-common icinga2-bin icinga2
+rm -rf /var/lib/icinga2
+rm -rf /etc/icinga2
+```
 
 ## Remove Old Hostname