Add reference to zero touch provisioning blog in docs

While not proper documentation, this should help people follow the ZTP
model.

Change-Id: If84a472826110bce151109ce80e70e1cef2a8177
Story: 2006640
Task: 37389

doc/source/deployment.rst

@@ -264,6 +264,13 @@ to add them to the Kayobe and Kolla-Ansible inventories::
 
     (kayobe) $ kayobe overcloud inventory discover
 
+.. seealso::
+
+   This `blog post <https://www.stackhpc.com/ironic-idrac-ztp.html>`__
+   provides a case study of the discovery process, including automatically
+   naming Ironic nodes via switch port descriptions, Ironic Inspector and
+   LLDP.
+
 Saving Hardware Introspection Data
 ----------------------------------