chore: remove codefund badge, update license badge (#3229)

Removes broken code fund badge and updates the license badge to point at this repository.

README.md

@@ -1,8 +1,7 @@
 # Insomnia REST Client
 
 [![Slack Channel](https://chat.insomnia.rest/badge.svg)](https://chat.insomnia.rest/)
-[![license](https://img.shields.io/github/license/mashape/apistatus.svg)](https://github.com/Kong/insomnia/blob/master/LICENSE)
-[![CodeFund](https://img.shields.io/badge/codefund-advertiser-success.svg)](https://codefund.io)
+[![license](https://img.shields.io/github/license/Kong/insomnia.svg)](https://github.com/Kong/insomnia/blob/master/LICENSE)
 
 Insomnia is a cross-platform _REST client_, built on top of [Electron](http://electron.atom.io/).