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/application-architect.md

@@ -0,0 +1,44 @@
+---
+title: 应用架构师（Application Architect）
+id: application-architect
+date: 2018-04-12
+full_link: 
+short_description: >
+  应用架构师是负责应用高级设计的人。
+
+aka: 
+tags:
+- user-type
+---
+
+<!--
+---
+title: Application Architect
+id: application-architect
+date: 2018-04-12
+full_link: 
+short_description: >
+  A person responsible for the high-level design of an application.
+
+aka: 
+tags:
+- user-type
+---
+-->
+
+<!--
+ A person responsible for the high-level design of an application.
+-->
+ 应用架构师是负责应用高级设计的人。
+
+			
+
+
+<!--more--> 
+<!--
+An architect ensures that an app's implementation allows it to interact with its surrounding components in a scalable, maintainable way. Surrounding components include databases, logging infrastructure, and other microservices.
+-->
+
+应用架构师确保应用的实现允许它和周边组件进行可扩展的、可持续的交互。
+周边组件包括数据库、日志基础设施和其他微服务。
+