doc: add note about wildcard certs

Author: mnaser

roles/openstack_helm_ingress/README.md

@@ -7,18 +7,24 @@ with Atmosphere, you can simply configure it as follows;
 
 1. Create a Kubernetes TLS secret using your wildcard certificate, you can refer
    to the [Kubernetes documentation](https://kubernetes.io/docs/concepts/configuration/secret/#tls-secrets)
-    for more details.
+   for more details.
 
-    ```shell
-    kubectl -n openstack create secret tls wildcard-certs --key=/path/to/tls.key --cert=/path/to/tls.crt
-    ```
+   ```shell
+   kubectl -n openstack create secret tls wildcard-certs --key=/path/to/tls.key --cert=/path/to/tls.crt
+   ```
+
+   > **Note**
+   >
+   > If you have a certificate that needs to be combined with an intermediate
+   > certificate, you can combine them all to a single file with the certificate
+   > first, followed by the intermediate certificate, followed by the root.
 
 2. Update the `openstack_helm_ingress_secret_name` to point towards the name
    of the secret you created in step 1.
 
-    ```yaml
-    openstack_helm_ingress_secret_name: wildcard-certs
-    ```
+   ```yaml
+   openstack_helm_ingress_secret_name: wildcard-certs
+   ```
 
 > **Note**
 >