Testling, missing .png

Hey there,

there is a missing .png in the Readme file ;). Also wanted to let you know that for the github hooks for testling you need to set.

Also it seems like there is no Github webhook. You need to add those in [the projects settings](https://github.com/sethvincent/crtrdg-gameloop/settings/hooks). You need to put it on `application/x-www-form-urlencoded`, which doesn't seem to be documented anywhere. But this way it works.

 Best,
Finn