Update docs markdown file weight to make it clear (#23909)

For Docusaurus, it needs a meta data named `sidebar_position`, so we
copy all `weight` under `menu/sidebar` as top meta key.

docs/content/doc/installation/on-kubernetes.en-us.md

@@ -2,14 +2,14 @@
 date: "2020-03-19T19:27:00+02:00"
 title: "Install on Kubernetes"
 slug: "install-on-kubernetes"
-weight: 10
+weight: 80
 toc: false
 draft: false
 menu:
   sidebar:
     parent: "installation"
     name: "Kubernetes"
-    weight: 50
+    weight: 80
     identifier: "install-on-kubernetes"
 ---