Update README

Author: apertureless

README.md

@@ -5,6 +5,8 @@
 [![vue2](https://img.shields.io/badge/vue-2.x-brightgreen.svg)](https://vuejs.org/)
 [![license](https://img.shields.io/github/license/mashape/apistatus.svg)](https://github.com/apertureless/vue-password-strength-meter/blob/master/LICENSE.txt)
 
+[![ko-fi](https://www.ko-fi.com/img/githubbutton_sm.svg)](https://ko-fi.com/C0C1WP7C)
+
 Interactive password strength meter based on [zxcvbn](https://github.com/dropbox/zxcvbn) for vue.js
 
 <p align="center">