docs(migrate): convert CJS config examples to ESM (webpack#7981)

Author: ItsAbir005

src/content/migrate/5.mdx

@@ -98,7 +98,7 @@ T> Checkout the detailed changes in the configuration options [here](/blog/2020-
 Try to set the following options in your webpack 4 configuration and check if build still works correctly.
 
 ```javascript
-module.exports = {
+export default {
   // ...
   node: {
     Buffer: false,

src/content/plugins/environment-plugin.mdx

@@ -94,10 +94,10 @@ if ("false") {
 The following `EnvironmentPlugin` configuration provides `process.env.GIT_VERSION` (such as "v5.4.0-2-g25139f57f") and `process.env.GIT_AUTHOR_DATE` (such as "2020-11-04T12:25:16+01:00") corresponding to the last Git commit of the repository:
 
 ```javascript
-const child_process = require("node:child_process");
+import childProcess from "node:child_process";
 
 function git(command) {
-  return child_process.execSync(`git ${command}`, { encoding: "utf8" }).trim();
+  return childProcess.execSync(`git ${command}`, { encoding: "utf8" }).trim();
 }
 
 new webpack.EnvironmentPlugin({