Updates the File patterns attribute to note that .. is not supported

See discussion at: https://github.com/CocoaPods/CocoaPods/issues/1259

![screen shot 2013-08-06 at 11 48 27 am](https://f.cloud.github.com/assets/1274145/919439/4180ee5c-fec9-11e2-997e-23dd972bdcda.png)