add migration guide for updated cron monitoring features (#12617)

Author: gaprl

docs/product/crons/alerts-backend-insights-migration.mdx

@@ -0,0 +1,21 @@
+---
+title: Cron Monitoring Updates for Developers
+noindex: true
+draft: true
+sidebar_hidden: true
+---
+
+The **Cron Monitoring** feature has been relocated and restructured to improve accessibility and functionality. Previously, it was found in the sidebar under **"Crons"**, but it has now been split into two different locations:
+
+## Timeline View (Overview of Cron Jobs)
+
+- The timeline view that provided an overview of all cron jobs has moved.
+- You can now find it under **Insights > Backend > Cron Monitors (Tab)**.
+  ![Screenshot showing new location](img/crons-as-backend-insights.png)
+
+## Managing Cron Monitors
+
+- The section for managing all of your cron monitors is now under **Alerts**.
+- **Cron Monitors are now a new type of Sentry Alert**, allowing for better integration and management within the Alerts system.
+- To filter and view all cron monitors easily, use the **Alert Type** filter for "Cron Monitors".
+  ![Screenshot showing Alerts menu and filter](img/crons-as-alerts-guide.png)