Merge pull request #22766 from gaoguangze111/update-architecture-index

Update concepts/architecture/_index.md

Author: k8s-ci-robot

content/zh/docs/concepts/architecture/_index.md

@@ -1,4 +1,6 @@
 ---
 title: "Kubernetes 架构"
 weight: 30
+description: >
+  Kubernetes 背后的架构概念。
 ---