Remove unnecessary meta data on markdown files (#12)

Reviewed-on: https://gitea.com/gitea/docs/pulls/12

docs/installation/on-kubernetes.md

@@ -3,16 +3,8 @@ date: "2020-03-19T19:27:00+02:00"
 title: "Install on Kubernetes"
 slug: "install-on-kubernetes"
 sidebar_position: 80
-toc: false
-draft: false
 aliases:
   - /en-us/install-on-kubernetes
-menu:
-  sidebar:
-    parent: "installation"
-    name: "Kubernetes"
-    sidebar_position: 80
-    identifier: "install-on-kubernetes"
 ---
 
 # Installation with Helm (on Kubernetes)