Update API routes documentation to correctly mention middlewar… (#11083)

Previously we said "Micro middlewares" but Next.js does not use micro. This would confuse users as both Next.js and Micro were created by ZEIT and Next.js API routes have different semantics than Micro handlers.

I've updated the docs to show how to use the `cors` middleware that's generally used in express apps.

docs/api-routes/api-middlewares.md

@@ -48,32 +48,51 @@ export const config = {
 }
 ```
 
-## Micro support
+## Connect/Express middleware support
 
-As an added bonus, you can also use any [Micro](https://github.com/zeit/micro) compatible middleware.
+You can also use [Connect](https://github.com/senchalabs/connect) compatible middleware.
 
-For example, [configuring CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) for your API endpoint can be done leveraging [micro-cors](https://github.com/possibilities/micro-cors).
+For example, [configuring CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) for your API endpoint can be done leveraging the [cors](https://www.npmjs.com/package/cors) package.
 
-First, install `micro-cors`:
+First, install `cors`:
 
 ```bash
-npm i micro-cors
+npm i cors
 # or
-yarn add micro-cors
+yarn add cors
 ```
 
-Now, let's add `micro-cors` to the API route:
+Now, let's add `cors` to the API route:
 
 ```js
-import Cors from 'micro-cors'
+import Cors from 'cors'
 
+// Initializing the cors middleware
 const cors = Cors({
-  allowMethods: ['GET', 'HEAD'],
+  methods: ['GET', 'HEAD'],
 })
 
-function handler(req, res) {
+// Helper method to wait for a middleware to execute before continuing
+// And to throw an error when an error happens in a middleware
+function runMiddleware(req, res, fn) {
+  return new Promise((resolve, reject) => {
+    fn(req, res, result => {
+      if (result instanceof Error) {
+        return reject(result)
+      }
+
+      return resolve(result)
+    })
+  })
+}
+
+async function handler(req, res) {
+  // Run the middleware
+  await runMiddleware(req, res, cors)
+
+  // Rest of the API logic
   res.json({ message: 'Hello Everyone!' })
 }
 
-export default cors(handler)
+export default handler
 ```