Added note in machine configuration tasks.

Author: subhtk

post_installation_configuration/machine-configuration-tasks.adoc

@@ -12,6 +12,13 @@ Aside from a few specialized features, most changes to operating systems on {pro
 
 Tasks in this section describe how to use features of the Machine Config Operator to configure operating system features on {product-title} nodes.
 
+[IMPORTANT]
+====
+NetworkManager stores new network configurations to `/etc/NetworkManager/system-connections/` in a key file format
+
+Previously, NetworkManager stored new network configurations to `/etc/sysconfig/network-scripts/` in the ifcfg format. Starting with RHEL 9.0, RHEL stores new network configurations at `/etc/NetworkManager/system-connections/` in a key file format. The connections configurations stored to `/etc/sysconfig/network-scripts/` in the old format still work uninterrupted. Modifications in existing profiles continue updating the older files.
+====
+
 [id="understanding-the-machine-config-operator"]
 == Understanding the Machine Config Operator