test: add cross-link to token-refresh in RN login-pkce README

Verifies the trickiest path-aware filter case: an RN sample change
outside the `android/` subdir should still trigger the Android matrix
via the watch_root walk-up to package.json. Also exercises the JS
matrix's direct subtree match and proves iOS/.NET/Java workflows
correctly skip via empty matrix.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ksroda-sa

samples/react-native/login-pkce/README.md

@@ -2,6 +2,8 @@
 
 Minimal React Native app demonstrating OIDC login using Authorization Code + PKCE via [`react-native-app-auth`](https://github.com/FormidableLabs/react-native-app-auth). The system browser (ASWebAuthenticationSession on iOS, Custom Tabs on Android) handles the auth UI — never an embedded WebView.
 
+> Looking for the token-refresh variant? See [`samples/react-native/token-refresh/`](../token-refresh/).
+
 ## Prerequisites
 
 - Node 22.11+