Fix #selector usage in README and docs

Author: kean

CHANGELOG.md

@@ -68,7 +68,7 @@ RAC 5.0 includes a few object interception tools from ReactiveObjC, remastered f
 
 	```swift
 	// Notify after every time `viewWillAppear(_:)` is called.
-	let appearing = view.reactive.trigger(for: #selector(viewWillAppear(_:)))
+	let appearing = viewController.reactive.trigger(for: #selector(UIViewController.viewWillAppear(_:)))
 	```
 
 1. **Object Lifetime**

Documentation/README.md

@@ -22,7 +22,7 @@ ReactiveCocoa includes a few object interception tools from ReactiveObjC, remast
 
     ```swift
     // Notify after every time `viewWillAppear(_:)` is called.
-    let appearing = view.reactive.trigger(for: #selector(viewWillAppear(_:)))
+    let appearing = viewController.reactive.trigger(for: #selector(UIViewController.viewWillAppear(_:)))
     ```
 
 1. **Object Lifetime**

README.md

@@ -61,7 +61,7 @@ __ReactiveCocoa__ wraps various aspects of Cocoa frameworks with the declarative
 
 	```swift
 	// Notify after every time `viewWillAppear(_:)` is called.
-	let appearing = view.reactive.trigger(for: #selector(viewWillAppear(_:)))
+	let appearing = viewController.reactive.trigger(for: #selector(UIViewController.viewWillAppear(_:)))
 
 	// Observe the lifetime of `object`.
 	object.reactive.lifetime.ended.observeCompleted(doCleanup)