Merge pull request #14271 from occ/docs-nixos-containerd

docs: Add a note for NixOS and containerd

Documentation/Getting-Started/Prerequisites/prerequisites.md

@@ -129,3 +129,11 @@ ConfigMap found in operator.yaml:
 * `CSI_CEPHFS_PLUGIN_VOLUME_MOUNT`
 * `CSI_RBD_PLUGIN_VOLUME`
 * `CSI_RBD_PLUGIN_VOLUME_MOUNT`
+
+If using containerd, remove `LimitNOFILE` from containerd service config to avoid issues like slow ceph commands or mons falling out of quorum.
+
+```nix
+systemd.services.containerd.serviceConfig = {
+  LimitNOFILE = lib.mkForce null;
+};
+```