Missing documentation for splitting different entry points

From the README:

> The webpack-stats-plugin can be configured to split up separate stats files if desired in any manner (including splitting per entry point), but this is a more advanced usage not included in this document.

This is not available anywhere, how does one split the output into multiple files without knowledge of how the Webpack compiler works?

Related to https://github.com/FormidableLabs/webpack-stats-plugin/issues/43