chore：Fix some typos in Chinese and English (#3514)

docs/source/en/intro/egg-and-koa.md

@@ -25,7 +25,7 @@ fn().then(res => console.log(res)).catch(err => console.error(err.stack));
 
 ## Koa
 
-> Koa is a new Web framework designed by the team behind Express, which aims to be a smaller, more expressive, and more robust foundation for Web applications and APIs.
+> [Koa](https://koajs.com/) is a new Web framework designed by the team behind Express, which aims to be a smaller, more expressive, and more robust foundation for Web applications and APIs.
 
 The design styles of Koa and Express are very similar, The underlying basic library is the same, [HTTP library](https://github.com/jshttp). There are several significant differences between them. Besides the asynchronous solution by default mentioned above, there are the following points.
 

docs/source/en/style-guide.md

@@ -5,8 +5,9 @@ Developers are advised to use `egg-init --type=simple showcase` to generate and
 
 ## Classify
 
+Old Style:
+
 ```js
-// old style
 module.exports = app => {
   class UserService extends app.Service {
     async list() {

docs/source/en/tutorials/progressive.md

@@ -126,8 +126,8 @@ Codes refer to  [step3/egg-ua](https://github.com/eggjs/examples/tree/master/pro
 Then modify the application, details refer to [step3/example-app](https://github.com/eggjs/examples/tree/master/progressive/step3/example-app).
 
 - Remove directory `lib/plugin/egg-ua`.
-- declare dependencies `egg-ua`  in `package.json`.
-- change type to `package` in `config/plugin.js`.
+- Declare dependencies `egg-ua`  in `package.json`.
+- Change type to `package` in `config/plugin.js`.
 
 ```js
 // config/plugin.js
@@ -210,10 +210,10 @@ $ npm test
 In conclusion, we can see how to make the framework evolution step by step which benefits from Egg's powerful plugin mechanism, code co-build, reusability and modularity.
 
 
-- in general, put codes into `lib/plugin` if they can be reused in the application.
-- separate it into a `node module` when plugin becomes stable.
-- application with relatively reusable codes will work as a separate plugin.
-- abstract it as framework to release after application become certain solutions of specified business scenario.
-- it would be a great improvement in the efficiency of teamwork after plugins were extracted, modularized and finally became a framework, because other projects could reuse codes by just using `npm install`.
+- In general, put codes into `lib/plugin` if they can be reused in the application.
+- Separate it into a `node module` when plugin becomes stable.
+- Application with relatively reusable codes will work as a separate plugin.
+- Abstract it as framework to release after application become certain solutions of specified business scenario.
+- It would be a great improvement in the efficiency of teamwork after plugins were extracted, modularized and finally became a framework, because other projects could reuse codes by just using `npm install`.
 
 - **Note：Whether it's the application/plugin/framework, unittest is necessary and try to reach 100% coverage**

docs/source/zh-cn/faq.md

@@ -3,7 +3,7 @@ title: 常见问题
 
 如果下面的内容无法解决你的问题，请查看 [Egg issues](https://github.com/eggjs/egg/issues)。
 
-## 如何高效的反馈问题？
+## 如何高效地反馈问题？
 
 感谢您向我们反馈问题。
 
@@ -85,8 +85,8 @@ Egg 内置的 [egg-security](https://github.com/eggjs/egg-security/) 插件默
 
 没有自动重启的情况一般是在使用 Jetbrains 旗下软件（IntelliJ IDEA, WebStorm..），并且开启了 Safe Write 选项。
 
-Jetbrains [Safe Write 文档](https://www.jetbrains.com/help/webstorm/2016.3/system-settings.html)中有提到：
+Jetbrains [Safe Write 文档](https://www.jetbrains.com/help/webstorm/2016.3/system-settings.html)中有提到（翻译如下）：
 
-> If this check box is selected, a changed file is first saved in a temporary file. If the save operation succeeds, the file being saved is replaced with the saved file. (Technically, the original file is deleted and the temporary file is renamed.)
+> 如果此复选框打钩，变更的文件将首先被存储在一个临时文件中。如果成功保存了该文件，那么就会被这个文件所取代（从技术上来说，原文件被删除，临时文件被重命名）。
 
 由于使用了重命名导致文件监听的失效。解决办法是关掉 Safe Write 选项。（Settings | Appearance & Behavior | System Settings | Use "safe write" 路径可能根据版本有所不同）

docs/source/zh-cn/intro/egg-and-koa.md

@@ -25,7 +25,7 @@ fn().then(res => console.log(res)).catch(err => console.error(err.stack));
 
 ## Koa
 
-> Koa is a new Web framework designed by the team behind Express, which aims to be a smaller, more expressive, and more robust foundation for Web applications and APIs.
+> [Koa](https://koajs.com/) 是一个新的 web 框架，由 Express 幕后的原班人马打造， 致力于成为 web 应用和 API 开发领域中的一个更小、更富有表现力、更健壮的基石。
 
 Koa 和 Express 的设计风格非常类似，底层也都是共用的[同一套 HTTP 基础库](https://github.com/jshttp)，但是有几个显著的区别，除了上面提到的默认异步解决方案之外，主要的特点还有下面几个。
 

docs/source/zh-cn/style-guide.md

@@ -3,10 +3,11 @@ title: 代码风格指南
 
 建议开发者使用 `egg-init --type=simple showcase` 来生成并观察推荐的项目结构和配置。
 
-## Classify
+## 用类的形式呈现（Classify）
+
+旧写法：
 
 ```js
-// old style
 module.exports = app => {
   class UserService extends app.Service {
     async list() {
@@ -42,7 +43,7 @@ module.export = Object.assign(egg, {
 });
 ```
 
-## Private property && Lazy Initialization
+## 私有属性与慢初始化
 
 - 私有属性用 `Symbol` 来挂载。
 - Symbol 的描述遵循 jsdoc 的规则，描述映射后的类名+属性名。

docs/source/zh-cn/tutorials/progressive.md

@@ -14,7 +14,7 @@ title: 渐进式开发
 - `ctx.isAndroid`
 - `ctx.isIOS`
 
-通过之前的教程，大家一定可以很快的写出来，我们快速回顾下：
+通过之前的教程，大家一定可以很快地写出来，我们快速回顾下：
 
 对应的代码参见 [step1](https://github.com/eggjs/examples/tree/master/progressive/step1)。
 
@@ -207,7 +207,7 @@ $ npm test
 
 ## 写在最后
 
-综上所述，大家可以看到，我们是如何一步步渐进的去进行框架演进，得益于 Egg 强大的插件机制，代码的共建，复用和下沉，竟然可以这么的无痛。
+综上所述，大家可以看到我们是如何一步步渐进地去进行框架演进，这得益于 Egg 强大的插件机制、代码的共建，以及复用和下沉，这些步骤竟然可以这么地无痛来得以完成！
 
 - 一般来说，当应用中有可能会复用到的代码时，直接放到 `lib/plugin` 目录去，如例子中的 `egg-ua`。
 - 当该插件功能稳定后，即可独立出来作为一个 `node module` 。