Missing doc comments

Author: neilpa

Source/Foundation/NSData.swift

@@ -10,8 +10,7 @@ import Foundation
 import ReactiveCocoa
 
 extension NSData {
-    /// Read the data at the URL.
-    /// Sends the data or the error.
+    /// Read the data at the URL, sending the result or an error.
     public class func rex_dataWithContentsOfURL(url: NSURL, options: NSDataReadingOptions = NSDataReadingOptions()) -> SignalProducer<NSData, NSError> {
         return SignalProducer<NSData, NSError> { observer, disposable in
             do {

Source/UIKit/UILabel.swift

@@ -14,7 +14,8 @@ extension UILabel {
     public var rex_text: MutableProperty<String> {
         return associatedProperty(self, keyPath: "text")
     }
-    
+
+    /// Wraps a label's `textColor` value in a bindable property.
     public var rex_textColor: MutableProperty<UIColor> {
         return associatedProperty(self, key: &textColor, initial: { $0.textColor }, setter: { $0.textColor = $1 })
     }