docs(Omada-Controller): Add DHCP Option 138 for APs (#4285)

* docs(Omada-Controller): Add DHCP Option 138

* add image for DHCP 138

charts/stable/omada-controller/Chart.yaml

@@ -18,7 +18,7 @@ name: omada-controller
 sources:
   - https://github.com/truecharts/charts/tree/master/charts/stable/omada-controller
   - https://github.com/mbentley/docker-omada-controller
-version: 6.3.1
+version: 6.3.2
 annotations:
   truecharts.org/catagories: |
     - media

charts/stable/omada-controller/docs/installation_notes.md

@@ -19,3 +19,9 @@ By default the `omada-controller` chart doesn't support discovery by APs on the
 - Please follow the directions on the [TP-Link Website](https://www.tp-link.com/us/support/download/omada-software-controller/#Omada_Discovery_Utility) to download and use this utility. They have a nice [FAQ](https://www.tp-link.com/ca/support/faq/3087/) that may be of use.
 
 ![Omada-Discovery-Utility](img/Omada-Discovery-Utility.png)
+
+## DHCP Option 138
+
+As well, the `Omada-Controller` supports using DHCP to inform your APs of the location of the controller. This can be done using the `Omada` software or another DHCP server such as `OPNsense`. This has been tested by users (see [TP-Link Reddit](https://www.reddit.com/r/TPLink_Omada/comments/wv8nsi/omada_sdn_controller_eap_discovery_across/) for more info) but there's a reference guide available in the official [Omada SDN Software Controller](https://www.tp-link.com/us/user-guides/omada-sdn-software-controller/chapter-3-manage-omada-managed-devices-and-sites.html#ug-sub-title-2) users guide.
+
+![DHCP-Option-138](img/dhcp-option-138.png)