remove experimental note about CentOS 8 and derivatives (#7615)

README.md

@@ -117,12 +117,12 @@ vagrant up
 - **Flatcar Container Linux by Kinvolk**
 - **Debian** Buster, Jessie, Stretch, Wheezy
 - **Ubuntu** 16.04, 18.04, 20.04
-- **CentOS/RHEL** 7, 8 (experimental: see [centos 8 notes](docs/centos8.md))
+- **CentOS/RHEL** 7, [8](docs/centos8.md)
 - **Fedora** 32, 33
 - **Fedora CoreOS** (experimental: see [fcos Note](docs/fcos.md))
 - **openSUSE** Leap 15.x/Tumbleweed
-- **Oracle Linux** 7, 8 (experimental: [centos 8 notes](docs/centos8.md) apply)
-- **Alma Linux** 8 (experimental: [centos 8 notes](docs/centos8.md) apply)
+- **Oracle Linux** 7, [8](docs/centos8.md)
+- **Alma Linux** [8](docs/centos8.md)
 - **Amazon Linux 2** (experimental: see [amazon linux notes](docs/amazonlinux.md)
 
 Note: Upstart/SysV init based OS types are not supported.

docs/centos8.md

-# CentOS 8 / AlmaLinux 8
+# CentOS 8 and derivatives
 
-CentOS 8 / AlmaLinux 8 ships only with iptables-nft (ie without iptables-legacy)
+CentOS 8 / Oracle Linux 8 / AlmaLinux 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 use K8S 1.17+ and to add `calico_iptables_backend: "NFT"` or `calico_iptables_backend: "Auto"` to your configuration
+You need to add `calico_iptables_backend: "NFT"` or `calico_iptables_backend: "Auto"` 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.