Clarify missing specification and add examples

docusaurus/docs/proxying-api-requests-in-development.md

@@ -16,7 +16,7 @@ For example, a production setup might look like this after the app is deployed:
 
 Such setup is **not** required. However, if you **do** have a setup like this, it is convenient to write requests like `fetch('/api/todos')` without worrying about redirecting them to another host or port during development.
 
-To tell the development server to proxy any unknown requests to your API server in development, add a `proxy` field to your `package.json`, for example:
+To tell the development server to proxy any unknown requests to your API server in development, add a `proxy` field with a **string** value to your `package.json`, for example:
 
 ```json
   "proxy": "http://localhost:4000",
@@ -34,9 +34,9 @@ Keep in mind that `proxy` only has effect in development (with `npm start`), and
 
 The `proxy` option supports HTTP, HTTPS and WebSocket connections.
 
-If the `proxy` option is **not** flexible enough for you, alternatively you can:
+The `proxy` option only accepts a simple string as a value. If this is **not** flexible enough for you, alternatively you can:
 
-- [Configure the proxy yourself](#configuring-the-proxy-manually)
+- [Configure the proxy yourself](#configuring-the-proxy)
 - Enable CORS on your server ([here’s how to do it for Express](https://enable-cors.org/server_expressjs.html)).
 - Use [environment variables](adding-custom-environment-variables.md) to inject the right server host and port into your app.
 
@@ -66,11 +66,11 @@ DANGEROUSLY_DISABLE_HOST_CHECK=true
 
 We don’t recommend this approach.
 
-## Configuring the Proxy Manually
+## Configuring the Proxy
 
 > Note: this feature is available with `[email protected]` and higher.
 
-If the `proxy` option is **not** flexible enough for you, you can get direct access to the Express app instance and hook up your own proxy middleware.
+If the simple string value of the `proxy` option is **not** flexible enough for you, you can get direct access to the Express app instance and hook up your own proxy middleware.
 
 You can use this feature in conjunction with the `proxy` property in `package.json`, but it is recommended you consolidate all of your logic into `src/setupProxy.js`.
 
@@ -85,7 +85,7 @@ $ yarn add http-proxy-middleware
 Next, create `src/setupProxy.js` and place the following contents in it:
 
 ```js
-const { createProxyMiddleware } = require('http-proxy-middleware');
+const createProxyMiddleware = require('http-proxy-middleware');
 
 module.exports = function(app) {
   // ...
@@ -95,7 +95,7 @@ module.exports = function(app) {
 You can now register proxies as you wish! Here's an example using the above `http-proxy-middleware`:
 
 ```js
-const { createProxyMiddleware } = require('http-proxy-middleware');
+const createProxyMiddleware = require('http-proxy-middleware');
 
 module.exports = function(app) {
   app.use(
@@ -108,6 +108,29 @@ module.exports = function(app) {
 };
 ```
 
+Another example with multiple proxies:
+
+```js
+const createProxyMiddleware = require('http-proxy-middleware');
+
+module.exports = function(app) {
+  app.use(
+    '/api/v0',
+    createProxyMiddleware({
+      target: 'http://localhost:5000',
+      changeOrigin: true,
+    })
+  );
+  app.use(
+    '/api/v1',
+    createProxyMiddleware({
+      target: 'http://localhost:5001',
+      changeOrigin: true,
+    })
+  );
+};
+```
+
 > **Note:** You do not need to import this file anywhere. It is automatically registered when you start the development server.
 
 > **Note:** This file only supports Node's JavaScript syntax. Be sure to only use supported language features (i.e. no support for Flow, ES Modules, etc).