Update index.html

change image (small) https://cloud.githubusercontent.com/assets/5073946/3721751/7d4b2a12-1663-11e4-9b1e-2dcfd32a6968.png to image (smaller) https://cloud.githubusercontent.com/assets/5073946/3721788/eed761b4-1663-11e4-85cf-18776831a464.png