add image to README

Author: tenntenn

README.md

@@ -2,3 +2,9 @@ gopher-3d
 =========
 
 Gopher 3D model
+
+<img width="50%" src="https://raw.github.com/golang-samples/gopher-3d/master/gopher3d.png"/>
+
+<a rel="license" href="http://creativecommons.org/licenses/by/3.0/deed.ja">
+    <img alt="Creative Commons licensing" style="border-width:0" src="http://i.creativecommons.org/l/by/3.0/88x31.png" />
+</a>