remove es6 config docs

Author: koddsson

docs/configs.md

@@ -22,9 +22,6 @@ $ node_modules/.bin/eslint-github-init
 
 A base layer of configuration recommended for any JS project. The [Prettier](https://prettier.io/) formatter is used to format code.
 
-### `plugin:github/es6`
-
-Recommended rules when using Babel to transpile features from ES2015+.
 
 ### `plugin:github/app`