Remove obsolete doc

Author: alexeyr

docs/guides/rails-webpacker-react-integration-options.md

@@ -56,36 +56,6 @@ document.addEventListener('DOMContentLoaded', () => {
 
 ---
 
-## Suppress warning related to Can't resolve 'react-dom/client' in React < 18
-
-You may see a warning like this when building a Webpack bundle using any version of React below 18:
-
-```
-Module not found: Error: Can't resolve 'react-dom/client' in ....
-```
-
-It can be safely [suppressed](https://webpack.js.org/configuration/other-options/#ignorewarnings) in your Webpack configuration. The following is an example of this suppression in `config/webpack/commonWebpackConfig.js`:
-
-```js
-const { webpackConfig: baseClientWebpackConfig, merge } = require('shakapacker');
-
-const commonOptions = {
-  resolve: {
-    extensions: ['.css', '.ts', '.tsx'],
-  },
-};
-
-const ignoreWarningsConfig = {
-  ignoreWarnings: [/Module not found: Error: Can't resolve 'react-dom\/client'/],
-};
-
-const commonWebpackConfig = () => merge({}, baseClientWebpackConfig, commonOptions, ignoreWarningsConfig);
-
-module.exports = commonWebpackConfig;
-```
-
----
-
 ## HMR and React Hot Reloading
 
 Before turning HMR on, consider upgrading to the latest stable gems and packages: