No bug: update root url in cron description in `.taskcluster.yml`; r=aki

Differential Revision: https://phabricator.services.mozilla.com/D82246

.taskcluster.yml

@@ -95,7 +95,7 @@ tasks:
                                     Action triggered by clientID `${clientId}`
                             else:
                                 name: "Decision Task for cron job ${cron.job_name}"
-                                description: 'Created by a [cron task](https://tools.taskcluster.net/tasks/${cron.task_id})'
+                                description: 'Created by a [cron task](https://firefox-ci-tc.services.mozilla.com/tasks/${cron.task_id})'
 
               provisionerId: "${trust_domain}-${repository.level}"
               workerType: "decision"