Merge pull request #26186 from ydFu/update-install-kubeadm

Update install-kubeadm.md

Author: k8s-ci-robot

content/zh/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md

@@ -33,8 +33,8 @@ For information how to create a cluster with kubeadm once you have performed thi
 * One or more machines running one of:
   - Ubuntu 16.04+
   - Debian 9+
-  - CentOS 7
-  - Red Hat Enterprise Linux (RHEL) 7
+  - CentOS 7+
+  - Red Hat Enterprise Linux (RHEL) 7+
   - Fedora 25+
   - HypriotOS v1.0.1+
   - Flatcar Container Linux (tested with 2512.3.0)
@@ -48,8 +48,8 @@ For information how to create a cluster with kubeadm once you have performed thi
 * 一台或多台运行着下列系统的机器：
   - Ubuntu 16.04+
   - Debian 9+
-  - CentOS 7
-  - Red Hat Enterprise Linux (RHEL) 7
+  - CentOS 7+
+  - Red Hat Enterprise Linux (RHEL) 7+
   - Fedora 25+
   - HypriotOS v1.0.1+
   - Flatcar Container Linux （使用 2512.3.0 版本测试通过）