Update with-now-env to use env config (#6581)

* Update with-now-env to use `env` config
instead of webpack.DefinePlugin

* Remove mention of DefinePlugin from index page

examples/with-now-env/next.config.js

@@ -1,4 +1,3 @@
-const webpack = require('webpack')
 /**
  * After the next require you can use process.env to get your secrets
  */
@@ -18,14 +17,7 @@ console.log({
  * to share some variables with the client, configured at compile time.
  */
 module.exports = {
-  webpack: config => {
-    config.plugins.push(
-      new webpack.DefinePlugin({
-        'process.env.SECRET': JSON.stringify(process.env.SECRET)
-      })
-      // Same as above
-      // new webpack.EnvironmentPlugin(['SECRET'])
-    )
-    return config
+  env: {
+    SECRET: process.env.SECRET
   }
 }

examples/with-now-env/package.json

@@ -1,6 +1,6 @@
 {
   "name": "with-now-env",
-  "version": "1.0.0",
+  "version": "2.0.0",
   "scripts": {
     "dev": "next",
     "build": "next build",

examples/with-now-env/pages/index.js

@@ -1,8 +1,7 @@
 export default () => (
   <div className='hello'>
     <p>
-      Hello World! Here's a secret shared with the client using webpack
-      DefinePlugin: <strong>{process.env.SECRET}</strong>, the secret is shared
+      Hello World! Here's a secret shared with the client using Next env: <strong>{process.env.SECRET}</strong>, the secret is shared
       at compile time, which means every reference to the secret is replaced
       with its value
     </p>