In the main readme, please add syntax for usage in `chainWebpack` (as opposed to webpackConfig)

Under Usage (on main readme) you have the standard syntax about how to use this in webpack-config.
Would be excellent if you added also an alternative (of that same example) but in [chainWebpack ](https://github.com/neutrinojs/webpack-chain) format , as many people (including us) using Vue-Cli projects, are required to use `chainWebpack` config, and many people open help-topics (i.e. [like this](https://github.com/neutrinojs/webpack-chain/issues/124) )

thanks

Open the main README and find the Usage section containing the existing webpackConfig example. Add a parallel example showing the equivalent syntax for chainWebpack, using the linked webpack-chain format as reference. Done means the README documents both configuration approaches clearly.

Written by the indexing model from the issue text.