Document EDPMServiceType

Jira: https://issues.redhat.com/browse/OSPRH-7112
Signed-off-by: James Slagle <[email protected]>

docs/assemblies/proc_creating-a-custom-service.adoc

@@ -105,7 +105,19 @@ spec:
           delegate_to: localhost
   deployOnAllNodeSets: true
 ----
+
+. Optional: Specify the `edpmServiceType` field for the service. Different custom services may use the same ansible content to manage the same EDPM service (such as `ovn` or `nova`). The `ConfigMaps`, `Secrets`, TLS certificates, and CA certificates need to be mounted at the same locations so they can be found by the ansible content even when using a custom service. `edpmServiceType` is used to create this association. The value is the name of the default service that uses the same ansible content as the custom service.
++
+For example, a custom service that uses the `edpm_ovn` ansible content from `edpm-ansible` would set `edpmServiceType` to `ovn`, which matches the default `ovn` service name provided by `dataplane-operator`.
 +
+----
+apiVersion: dataplane.openstack.org/v1beta1
+kind: OpenStackDataPlaneService
+metadata:
+  name: custom-ovn-service
+spec:
+  edpmServiceType: ovn
+----
 
 . Create the custom service:
 +