Add Ko-fi button

Author: maoberlehner

README.md

@@ -6,7 +6,9 @@
 [![Coverage Status](https://coveralls.io/repos/github/maoberlehner/vuex-map-fields/badge.svg?branch=master)](https://coveralls.io/github/maoberlehner/vuex-map-fields?branch=master)
 [![GitHub stars](https://img.shields.io/github/stars/maoberlehner/vuex-map-fields.svg?style=social&label=Star)](https://github.com/maoberlehner/vuex-map-fields)
 
-Enable two-way data binding for form fields saved in a Vuex store.
+> Enable two-way data binding for form fields saved in a Vuex store.
+
+[![ko-fi](https://www.ko-fi.com/img/githubbutton_sm.svg)](https://ko-fi.com/O4O7U55Y)
 
 ## Install