title: How to use LESS in React 16.7 with webpack 4.29?
body: <p>I am just start to learn React, and I want to use less in React. I did some research about it , and they said I should write the config in <code>webpack.config.dev.js</code> but , after I run <code>npm run eject</code> I only got one file :<code>webpack.config.js</code> . </p>
  
  <p>I think maybe that's because the update , the new version maybe combined webpack.config.dev.js and webpack.config.prod.js to `webpack.config.js .</p>
  
  <p>and I checked the homepage of webpack , it says:</p>
  
  <pre><code>// webpack.config.js
  module.exports = {
    ...
    module: {
      rules: [{
        test: /\.js$/,
        issuer: /\.less$/,
        use: [{
          loader: 'js-to-less-loader'
        }]
      }]
    }
  };
  </code></pre>
  
  <p>but I don't know where to insert these code. I did not find any code like that.so I want a simple example for how to support less in React.</p>
  
  <p>Thanks.</p>