add a link to fibonacci spiral

Author: gitcheng

_posts/2015-01-24-golden-ratio-and-fibonacci-numbers.md

@@ -121,8 +121,8 @@ cut it anymore.
 It can be shown that to cut this rectangular forever, the only ratio
 you can start with is the golden ratio. If you start with a ratio of two
 adjacent Fibonacci numbers (can be very close to the godel ratio but not
-exactly), you will end up with a square, that is, the ratio of the sides
-is $$a_2/a_1$$.
+exactly), you will end up with [a square (or two)](http://www.mathsisfun.com/numbers/images/fibonacci-spiral.gif),
+that is, the ratio of the sides is $$a_2/a_1$$.