docs(devServer): add type array reference in contentBasePublicPath

[snitin315]

Feature to document
Recently DevServer added support of array type contentBasePublicPath.

Reference webpack-dev-server#2489

Need to update the docs for same -
https://webpack.js.org/configuration/dev-server/#devservercontentbasepublicpath
Author(s)

Additional information

I am willing to work on this issue and submit a pull request.