Switch language name 'zh' to 'zh-cn'

This is the first step to rename 'zh' to 'zh-cn'. There are several reasons why we rename the language name.

- The upstream docsy theme changed the language name, leading to many warnings during site build;
  The side-effect is that the i18n strings are no longer working.
- We believe renaming the language is the right thing to do, because this move can make room for other variants of Chinese language, such as 'zh-tw', 'zh-sg' etc.

There would be several follow-ups to this PR, such as fixing the intra-site links, adding redirects etc.

We will lock up changes to zh/zh-cn pages for the moment, until this one gets in.

This PR is based on commit cdad0a7342.

content/zh-cn/docs/reference/glossary/cloud-controller-manager.md

@@ -0,0 +1,49 @@
+---
+title: 云控制器管理器（Cloud Controller Manager）
+id: cloud-controller-manager
+date: 2018-04-12
+full_link: /zh/docs/concepts/architecture/cloud-controller/
+short_description: >
+  将 Kubernetes 与第三方云提供商进行集成的控制面组件。
+
+aka: 
+tags:
+- core-object
+- architecture
+- operation
+---
+<!--
+title: Cloud Controller Manager
+id: cloud-controller-manager
+date: 2018-04-12
+full_link: /docs/concepts/architecture/cloud-controller/
+short_description: >
+  Control plane component that integrates Kubernetes with third-party cloud providers.
+
+aka: 
+tags:
+- core-object
+- architecture
+- operation
+-->
+
+<!--
+ A Kubernetes {{< glossary_tooltip text="control plane" term_id="control-plane" >}} component
+that embeds cloud-specific control logic. The cloud controller manager lets you link your
+cluster into your cloud provider's API, and separates out the components that interact
+with that cloud platform from components that only interact with your cluster.
+-->
+`cloud-controller-manager` 是指嵌入特定云的控制逻辑之
+{{< glossary_tooltip text="控制平面" term_id="control-plane" >}}组件。
+`cloud-controller-manager` 允许你将你的集群连接到云提供商的 API 之上，
+并将与该云平台交互的组件同与你的集群交互的组件分离开来。
+
+<!--more--> 
+<!--
+By decoupling the interoperability logic between Kubernetes and the underlying cloud
+infrastructure, the cloud-controller-manager component enables cloud providers to release
+features at a different pace compared to the main Kubernetes project.
+-->
+通过分离 Kubernetes 和底层云基础设置之间的互操作性逻辑，
+`cloud-controller-manager` 组件使云提供商能够以不同于 Kubernetes 主项目的
+步调发布新特征。