Learn to code: Update 'what every girl needs to know' link to a working mirror

Fixes railsbridge#367

Author: tjgrathwell

sites/en/learn-to-code/learn-to-code.md

@@ -19,7 +19,7 @@ You may have never programmed before. Now you will.
   * most coding happens in a team
   * pair programming is awesome
 
-<http://marthakelly.github.io/blog/2012/05/30/what-every-girl-needs-to-know-about-programming/>
+<http://women2.com/2012/09/04/linda-liukas-what-every-girl-needs-to-know-about-programming/>
 
 # What is coding?