docs: add description of interceptor

Author: huturen

README-CN.MD

@@ -325,6 +325,34 @@ axios.post('https://www.api.com/reqinfo?abc=123', {xyz: 456}, {responseType: 'js
 ```
 
 
+#### 拦截器
+
+您可以拦截一个请求，执行某些操作，然后让原始请求继续执行并捕获响应，再执行另外一些操作。
+关于拦截器的更详细讨论，可以参考这个[issue](https://github.com/huturen/http-request-mock/issues/14)。
+
+
+```javascript
+// mock用例
+mocker.mock({
+  url: '//jsonplaceholder.typicode.com/',
+  response: async function(requestInfo) {
+    // 1. 拦截一个请求，并执行一些事情，这里打印一些请求信息
+    console.log('original request info: ', requestInfo);
+
+    // 2. 然后执行原始请求调用，捕获返回的请求
+    const res = await requestInfo.doOriginalCall();
+
+    // 3. 最后再做一些其它的事情
+    console.log('original response:', res);
+    return { code: 0, msg: 'ok', data: res.responseJson };
+  }
+});
+
+// 执行一个请求
+axios.get('https://jsonplaceholder.typicode.com/photos/1').then(res => console.log(res.data));
+```
+
+
 ## 项目整合
 对于简单项目来说，只要在项目入口引入`http-request-mock`并配置mok数据就可以用mock了, 以vue项目为例：
 ```javascript

README.MD

@@ -331,6 +331,33 @@ axios.post('https://www.api.com/reqinfo?abc=123', {xyz: 456}, {responseType: 'js
 ```
 
 
+
+#### Interceptor
+You can intercept a request, do something, then make the original call and capture the response and do something again.
+For more detailed discussions about the interceptor, please refer to this [issue](https://github.com/huturen/http-request-mock/issues/14).
+```javascript
+// mock case
+mocker.mock({
+  url: '//jsonplaceholder.typicode.com/',
+  response: async function(requestInfo) {
+    // 1. intercept a request, do something (here, output the original request information)
+    console.log('original request info: ', requestInfo);
+
+    // 2. then make the original call and capture the response
+    const res = await requestInfo.doOriginalCall();
+
+    // 3. and do something again.
+    console.log('original response:', res);
+    return { code: 0, msg: 'ok', data: res.responseJson };
+  }
+});
+
+// issue a request
+axios.get('https://jsonplaceholder.typicode.com/photos/1').then(res => console.log(res.data));
+```
+
+
+
 ## Integration
 In a bare-bones example, you just import `http-request-mock` into your application
 entry file(such as: src/main.js) and configure your mock datas there.

docs/interceptor.png

@@ -1,6 +1,6 @@
 {
   "name": "http-request-mock",
-  "version": "1.8.14",
+  "version": "1.8.15",
   "description": "Intercept & mock http requests issued by XMLHttpRequest, fetch, nodejs https/http module, axios, jquery, superagent, ky, node-fetch, request, got or any other request libraries by intercepting XMLHttpRequest, fetch and nodejs native requests in low level.",
   "main": "src/index.js",
   "module": "http-request-mock.esm.mjs",