Added attribution to NYTimes and Robots and Pencils in the Credits section.

Author: ndubbs

README.md

@@ -12,6 +12,8 @@ This style guide is different from other Objective-C style guides you may see, b
 
 The creation of this style guide was a collaborative effort from various raywenderlich.com team members under the direction of Nicholas Waynik.  The team includes: [Soheil Moayedi Azarpour](https://github.com/moayes), [Ricardo Rendon Cepeda](https://github.com/ricardo-rendoncepeda), [Tony Dahbura](https://github.com/tdahbura), [Colin Eberhardt](https://github.com/ColinEberhardt), [Matt Galloway](https://github.com/mattjgalloway), [Greg Heo](https://github.com/gregheo), [Matthijs Hollemans](https://github.com/hollance), [Christopher LaPollo](https://github.com/elephantronic), [Saul Mora](https://github.com/casademora), [Andy Pereira](https://github.com/macandyp), [Mic Pringle](https://github.com/micpringle), [Pietro Rea](https://github.com/pietrorea), [Cesare Rocchi](https://github.com/funkyboy), [Marin Todorov](https://github.com/icanzilb), [Nicholas Waynik](https://github.com/ndubbs), and [Ray Wenderlich](https://github.com/raywenderlich)
 
+We would like to thank the creators of the [New York Times](https://github.com/NYTimes/objective-c-style-guide) and [Robots & Pencils'](https://github.com/RobotsAndPencils/objective-c-style-guide) Objective-C Style Guides.  These two style guides provided a solid starting point for this guide to be created and based upon.
+
 ## Background
 
 Here are some of the documents from Apple that informed the style guide. If something isn't mentioned here, it's probably covered in great detail in one of these: