catalog-node: promote extension points

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

docs/backend-system/building-backends/08-migrating.md

@@ -660,7 +660,7 @@ depends on the appropriate extension point and interacts with it.
 
 ```ts title="packages/backend/src/index.ts"
 /* highlight-add-start */
-import { catalogProcessingExtensionPoint } from '@backstage/plugin-catalog-node/alpha';
+import { catalogProcessingExtensionPoint } from '@backstage/plugin-catalog-node';
 import { createBackendModule } from '@backstage/backend-plugin-api';
 /* highlight-add-end */