[minor] Fix indentation in NSDataDetectors example code

![screen shot 2013-06-06 at 01 21 34](https://f.cloud.github.com/assets/49038/615580/164c301c-ce3f-11e2-8c9b-2029ea1238b5.png)

I've aligned the spacing of the `NSDataDetector dataDetectorWithTypes:` method call for better visual pleasing-ness. I couldn't confirm as I don't have the whole Jekyll setup but I'd expect it to look better.