message: Fix wrong import in README.md
  Replace `identityApi` with `identityApiRef` when importing from
diff: @@ -54,7 +54,7 @@ To make use of the user settings backend, replace the `WebStorage` with the
  + discoveryApiRef,
  + fetchApiRef,
  errorApiRef,
  -+ identityApi,
  ++ identityApiRef,
  + storageApiRef,
  } from '@backstage/core-plugin-api';
  +import { UserSettingsStorage } from '@backstage/plugin-user-settings';
  