website/integrations: add note to nextcloud OIDC config (#15073)

Add note to OIDC config

website/integrations/services/nextcloud/index.mdx

@@ -161,6 +161,10 @@ Depending on your Nextcloud configuration, you may need to use `https://nextclou
 
     - **Use unique user ID**: If this option is disabled, Nextcloud will use the mapped user ID as the Federated Cloud ID.
 
+    :::note
+    If authentik and Nextcloud are running on the same host, you will need to add `'allow_local_remote_servers' => true` to your nextcloud `config.php` file. This setting allows remote servers with local addresses.
+    :::
+
     :::tip
     To avoid a hashed Federated Cloud ID, deselect **Use unique user ID** and use `user_id` for the User ID mapping.
     :::