Move old RHEL network manager info into admonition (#498)

* Move network manager disable into a admonition
* Truncate sysbox blog

Signed-off-by: Derek Nola <derek.nola@suse.com>

Author: dereknola

blog/2025-09-27-k3s-sysbox.md

@@ -2,12 +2,14 @@
 title: Sysbox Runtime With K3s
 description: Integrating sysbox runtime with k3s' containerd
 authors: husseingalal
-tags: ["runc","k3s","sysbox"]
+tags: ["runc","sysbox"]
 hide_table_of_contents: true
 ---
 
 The K3s binary bundles all the components needed to run a production-ready, CNCF-conformant Kubernetes cluster including containerd, runc, kubelet, and more. In this post we will discuss how containerd communicates with OCI runtimes and will discuss adding another container runtime (Sysbox) to K3s and how it can be used to run system pods in your environment.
 
+<!-- truncate -->
+
 ## Containerd and Runc
 
 First we need to talk briefly about how containerd works with runc. Containerd is a long running daemon that is responsible for:

docs/installation/requirements.md

@@ -66,11 +66,15 @@ firewall-cmd --reload
 
 Additional ports may need to be opened depending on your setup. See [Inbound Rules](#inbound-rules-for-k3s-nodes) for more information. If you change the default CIDR for pods or services, you will need to update the firewall rules accordingly.
 
-If enabled, it is required to disable nm-cloud-setup and reboot the node:
+:::warning Older RHEL/CentOS Releases
+
+OS versions prior to RHEL 8.4 carry NetworkManager with a known bug that interferes with K3s networking. If using an older release, it is required to disable nm-cloud-setup and reboot the node:
 ```bash
 systemctl disable nm-cloud-setup.service nm-cloud-setup.timer
 reboot
 ```
+:::
+
 </TabItem>
 <TabItem value="debian" label="Ubuntu / Debian">