Update README.md

Author: gsbernstein

README.md

@@ -7,7 +7,7 @@
 
 ## Example
 
-To run the example project, clone the repo, and run `pod install` from the Example directory first.
+~To run the example project, clone the repo, and run `pod install` from the Example directory first.~ Example project only used for testing so far
 
 ## Requirements
 
@@ -20,6 +20,24 @@ it, simply add the following line to your Podfile:
 pod 'constrain'
 ```
 
+## Usage
+
+This library lets you quickly and efficiently set up a number of constraints using intuitive chaining syntax. For example:
+
+```swift
+let containerView = UIView()
+let newView = UIView()
+let centeredView = UIView()
+containerView.constainSubview(newView).fillSafely()
+centeredView.constrainIn(containerView).center()
+```
+
+Notes:
+ - All constraints are enabled by default
+ - Adding subviews is handled by `constrainSubview()`, `constrainIn()`, `constrainSibling()`, `constrainSiblingToTrailing()`, or `constrainSiblingToBottom()`. If you need to add more constraints at a later time, just call `constrain` subsequently to avoid redoing it, although there's no harm in it.
+ - `translatesAutoresizingMaskIntoConstraints` is always set to false
+ - Most methods can also be called with View Controllers, but only the `constrainChild()` method handles parent/child UIViewController relationships. Call `remove()` to undo it.
+
 ## Author
 
 anconaesselmann, axel@anconaesselmann.com