[Frontend] Use Webpack disableHostCheck option in example

Author: javiereguiluz

frontend/encore/dev-server.rst

@@ -90,7 +90,7 @@ CORS Issues
 -----------
 
 If you experience issues related to CORS (Cross Origin Resource Sharing), set
-the ``firewall`` option:
+the following option:
 
 .. code-block:: javascript
 
@@ -101,11 +101,13 @@ the ``firewall`` option:
         // ...
 
         .configureDevServerOptions(options => {
-            options.firewall = false;
+            options.allowedHosts = 'all';
+            // in older Webpack Dev Server versions, use this option instead:
+            // options.firewall = false;
         })
 
-Beware that `it's not recommended to disable the firewall`_ in general, but
-here it's required to solve the CORS issue.
+Beware that this is not a recommended security practice in general, but here
+it's required to solve the CORS issue.
 
 Hot Module Replacement HMR
 --------------------------
@@ -123,5 +125,4 @@ your page. HMR works automatically with CSS (as long as you're using the
     CSS. That is no longer needed.
 
 .. _`webpack-dev-server`: https://webpack.js.org/configuration/dev-server/
-.. _`it's not recommended to disable the firewall`: https://webpack.js.org/configuration/dev-server/#devserverdisablehostcheck
 .. _`4.0 CHANGELOG`: https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md#400-beta0-2020-11-27