Add note in documentation: Mention that NodObjC apps cannot be approved on app stores

[ryandesign]

The readme says "you can write entire Cocoa or iOS GUI applications entirely in NodeJS JavaScript!" but fails to mention that such apps will not be approved for distribution on the primary distribution system for iOS or OS X: namely, the Apple app stores. See prior discussion:

https://groups.google.com/forum/#!msg/nodejs/7c_0hkdoEGY/NU9dikAuBhwJ

Please mention prominently in the readme that apps developed with NodObjC will not be approved on Apple app stores, so that developers who are interested in distributing their apps that way will not waste their time investigating NodObjC. Thanks.

[ghost]

Maybe entire apps written with nodobjc may not be approved, but I've used this module for access to Obj-C APIs that were previously inaccessible in NodeJS in applications that have passed the Apple Store Review Process.

See #94