Add better logo attribution. Thanks @marcker

README.md

@@ -22,7 +22,7 @@
 
 <p align="center">
 <a href="https://github.com/bpinto/oh-my-fish">
-<img width=50% src="https://cloud.githubusercontent.com/assets/958723/6883431/9beb62b0-d58b-11e4-902c-2f716859a7ad.png">
+<img width=40% src="https://cloud.githubusercontent.com/assets/958723/6883431/9beb62b0-d58b-11e4-902c-2f716859a7ad.png">
 </a>
 
 </p>
@@ -101,3 +101,5 @@ We are hoping to collect a bunch of themes for our command prompts. You can see
 ## License
 
 [MIT](http://mit-license.org) © [Contributors](https://github.com/bpinto/oh-my-fish/graphs/contributors)
+
+[Logo](https://cloud.githubusercontent.com/assets/958723/6847746/8d1b95b0-d3a7-11e4-866a-6bdc1eea0fe6.png) by [marcker](https://github.com/marcker):small_blue_diamond: [Attribution CC 4.0](http://creativecommons.org/licenses/by/4.0/)