docs(*): update documentation. add requirements for using lib moving forward

BREAKING CHANGE: moving into es2016+ language features

Author: web-mech

README.md

@@ -6,6 +6,10 @@ A javascript filter for badwords
 [![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/)
 [![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg?style=flat-square)](https://github.com/semantic-release/semantic-release)
 
+## Requirements
+
+As of version 2, requires you either have an environment that understands ES2016 and beyond or a transpiler like Babel.
+
 ## Installation
 
 ```