[Route] Update routes.js (#50472)

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remove if NA -->
**Related issue:** Resolves #48894 

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## Summary by CodeRabbit

* **New Features**
* Added a redirect from `/learn-more-about/removal-behavior` to the
relevant section of the custom OS settings guide.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

website/config/routes.js

@@ -1379,6 +1379,7 @@ module.exports.routes = {
   'GET /learn-more-about/idp-account-sync': '/guides/deploying-apple-account-provisioning-with-fleet',
   'GET /learn-more-about/security-posture': 'https://developers.google.com/android/management/reference/rest/v1/enterprises.devices#DevicePosture',
   'GET /learn-more-about/software-update-status': 'https://developers.google.com/android/management/reference/rest/v1/enterprises.devices#SystemUpdateInfo',
+  'GET /learn-more-about/removal-behavior': '/guides/custom-os-settings#removal-behavior',
 
 
   // Sitemap