docs(configuration): add link to migration guide for devServer v4 (#5314)

* docs(configuration): add link to migration guide for devServer v4

* use badge

* Update src/content/configuration/dev-server.mdx

Author: snitin315

src/content/configuration/dev-server.mdx

@@ -24,7 +24,7 @@ contributors:
 
 [webpack-dev-server](https://github.com/webpack/webpack-dev-server) can be used to quickly develop an application. See the [development guide](/guides/development/) to get started.
 
-This page describes the options that affect the behavior of webpack-dev-server (short: dev-server).
+This page describes the options that affect the behavior of webpack-dev-server (short: dev-server) <Badge text="version >= 4.0.0" />. Migration guide from `v3` to `v4` can be found [here](https://github.com/webpack/webpack-dev-server/blob/master/migration-v4.md).
 
 ## `devServer`