catalog-node: promote catalogServiceRef to main entry point

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

docs/backend-system/building-plugins-and-modules/08-migrating.md

@@ -39,7 +39,7 @@ import {
   coreServices,
   createBackendPlugin,
 } from '@backstage/backend-plugin-api';
-import { catalogServiceRef } from '@backstage/plugin-catalog-node/alpha';
+import { catalogServiceRef } from '@backstage/plugin-catalog-node';
 import { Router } from 'express';
 import { KubernetesBuilder } from './KubernetesBuilder';