reorganize banner and navigator

Signed-off-by: NCaspar Zhang <caspar@linux.alibaba.com>

CONTRIBUTING.md

-Contributing to Alibaba Cloud Linux Kernel
-==========================================
+Contributing Guide
+==================
+
++ [中文版开发者指南](zh/CONTRIBUTING.md)
 
 Table of Contents
 -----------------

CREDITS.md

 CREDITS
 =======
 
-> This is a credits-file of people that have contributed to Alibaba
-> Cloud Linux OS project and Alibaba Cloud Linux Kernel project.
+> This is a credits-file of teams and individuals that have contributed
+> to Alibaba Cloud Linux OS and Kernel projects.
 > The list is sorted by name. The fields are: name (N), email (E),
 > web-address (W) and description (D).
 

README.md

 Alibaba Cloud Linux Kernel
 ==========================
 
-Navigation | [中文版](zh/README.md) | [Alibaba Cloud Linux OS](os.md) | [CONTRIBUTING](CONTRIBUTING.md) | [CREDITS](CREDITS.md)
++ [中文版](zh/README.md)
 
 Table of Contents
 -----------------

_layouts/default.html

@@ -23,6 +23,9 @@
     <header class="page-header" role="banner">
       <h1 class="project-name">{{ page.title | default: site.title | default: site.github.repository_name }}</h1>
       <h2 class="project-tagline">{{ page.description | default: site.description | default: site.github.project_tagline }}</h2>
+      <a href="/cloud-kernel/" class="btn">Kernel</a>
+      <a href="/cloud-kernel/os.html" class="btn">OS</a>
+      <a href="/cloud-kernel/CONTRIBUTING.html" class="btn">Contributing Guide</a>
       {% if site.github.is_project_page %}
         <a href="{{ site.github.repository_url }}" class="btn">View on GitHub</a>
       {% endif %}

os.md

@@ -6,7 +6,7 @@ description: An open-source Linux distribution powered by Alibaba Cloud
 Brief Introduction to Alibaba Cloud Linux OS
 ============================================
 
-Navigation | [中文版](zh/os.md) | [Alibaba Cloud Linux Kernel](README.md) | [CONTRIBUTING](CONTRIBUTING.md) | [CREDITS](CREDITS.md)
++ [中文版](zh/os.md)
 
 Table of Contents
 -----------------

zh/CONTRIBUTING.md

 开发者指南
 ==========
 
++ [English Version of Contributing Guide](../CONTRIBUTING.md)
+
 目录
 ----
 1. [报告 BUG](#1-报告-bug)

zh/README.md

 阿里云 Linux 内核 (Alibaba Cloud Linux Kernel)
 ==============================================
 
-导航 | [English Version](../README.md) | [Alibaba Cloud Linux 操作系统](os.md) | [开发者指南](CONTRIBUTING.md) | [致谢](CREDITS.md)
++ [English Version](../README.md)
 
 目录
 ----

zh/os.md

@@ -6,7 +6,7 @@ description: 阿里云上原生的免费开源操作系统发行版
 Alibaba Cloud Linux 2 操作系统简介
 =================================
 
-导航 | [English Version](../os.md) | [阿里云 Linux 内核(ALK)](README.md) | [开发者指南](CONTRIBUTING.md) | [致谢](CREDITS.md)
++ [English Version](../os.md)
 
 目录
 ----