Add warning to beta release notes

docs/release-notes/version-4.0.md

@@ -2,6 +2,8 @@
 
 ## v4.0-beta1 (2024-04-03)
 
+**WARNING:** This is a beta release of NetBox intended for testing and evaluation. **Do not use this software in production.** Also be aware that no upgrade path is provided to future releases.
+
 !!! tip "Plugin Maintainers"
     Please see the dedicated [plugin migration guide](../plugins/development/migration-v4.md) for a checklist of changes that may be needed to ensure compatibility with NetBox v4.0.