Merge pull request #58569 from palonsoro/fix-users-not-supported

OCPBUGS-11688: Explained that adding new users is not supported

Author: mburke5678

modules/machine-config-overview.adoc

@@ -50,7 +50,7 @@ The kinds of components that MCO can change include:
 
 [IMPORTANT]
 ====
-Changing SSH keys via machine configs is only supported for the `core` user.
+Changing SSH keys via machine configs is only supported for the `core` user. It is not supported to add any other user via machine configs.
 ====
 * **kernelArguments**: Add arguments to the kernel command line when {product-title} nodes boot.
 * **kernelType**: Optionally identify a non-standard kernel to use instead of the standard kernel. Use `realtime` to use the RT kernel (for RAN). This is only supported on select platforms.