Docs: update README.md

Author: mysticatea

README.md

@@ -15,7 +15,7 @@ $ npm install --save-dev eslint eslint-plugin-node
 ```
 
 - Requires Node.js `>=6.0.0`
-- Requires ESLint `>=4.19.1`
+- Requires ESLint `>=4.19.1` (`plugin:node/recommended` preset requires `>=5.0.0`)
 
 **Note:** It recommends a use of [the "engines" field of package.json](https://docs.npmjs.com/files/package.json#engines). The "engines" field is used by `node/no-unsupported-features/*` rules.