Update the how-to diagram

Shows the new code hinting menu:

![howto](http://f.cl.ly/items/2s0r0W2q0G0O2o1F2D1a/Screen%20Shot%202013-05-29%20at%205.32.07%20PM.png "howto")

@larz0 If you want me to nudge the image in one direction or another, just say the word.

Addresses #117.