Update README.md

README.md

@@ -25,4 +25,6 @@ SAMBA_KEYTAB=/home/dehydrated/etc/dehydrated-service.keytab
 SAMBA_TICKETCACHE=/home/dehydrated/tmp/ticket-cache
 # wait for x seconds after deploying the challange to give the DNS time
 SAMBA_DNSWAIT=180
-```
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+```
+
+Last but not least, set `HOOK=/home/dehydrated/hooks/samba.sh` in `dehydrated.conf`.
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