suggest-to-use-nft-in-centos8 (#8987)

docs/centos.md

@@ -9,7 +9,7 @@ Kubespray supports multiple ansible versions but only the default (5.x) gets wid
 
 CentOS 8 / Oracle Linux 8 / AlmaLinux 8 / Rocky Linux 8 ship only with iptables-nft (ie without iptables-legacy similar to RHEL8)
 The only tested configuration for now is using Calico CNI
-You need to add `calico_iptables_backend: "NFT"` or `calico_iptables_backend: "Auto"` to your configuration.
+You need to add `calico_iptables_backend: "NFT"` to your configuration.
 
 If you have containers that are using iptables in the host network namespace (`hostNetwork=true`),
 you need to ensure they are using iptables-nft.