README.md in motion-kit-0.10.11 vs README.md in motion-kit-0.11.0

@@ -18,11 +18,11 @@
 5. Non-polluting
 6. ProMotion/RMQ/SugarCube-compatible (kind of goes hand-in-hand with being non-polluting)
 7. Styles and layouts are "just code" (not hash-based like in Teacup)
 8. Written by [the authors][authors] of [ProMotion][] and [Teacup][]
 
-[authors]: CONTRIBUTORS.md
+[authors]: CONTRIBUTORS.yaml
 [Colin]: https://github.com/colinta
 [Jamon]: https://github.com/jamonholmgren
 [ProMotion]: https://github.com/clearsightstudio/ProMotion
 [RMQ]: https://github.com/infinitered/rmq
 [Teacup]: https://github.com/rubymotion/teacup
@@ -113,10 +113,12 @@
   end
 
   def button_style
     # this will call 'setTitle(forState:)' via a UIButton helper
     title 'Press it!'
+    size_to_fit
+
     # this shorthand is much better!  More about frame helpers below.
     center ['50%', '50% + 50']
   end
 
 end
@@ -265,10 +267,36 @@
 
 end
 ```
 
 
+### Using child-layouts
+
+If you have a very complicated layout that you want to break up into child
+layouts, that is supported as well:
+
+```ruby
+class ParentLayout < MK::Layout
+
+  def layout
+    add ChildLayout, :child_id
+  end
+
+end
+```
+
+The id is (as always) optional, but allows you to fetch the layout using
+`get(id)`.
+
+```ruby
+layout.get(:child_id)  # => ChildLayout
+```
+
+Calling `get(:child_id).view` will return the *view* associated with that
+layout.
+
+
 ### Setting a custom root view
 
 If you need to use a custom root view, you can use the `root` method from within
 the `layout` method.  When you create or assign the root view this way, you must
 assign subviews and styles *inside* a block that you pass to `root`.
@@ -591,24 +619,34 @@
   x.is == 15
 
   # setting the priority:
   (x.is >= 10).priority(:required)
   (x.is == 15).priority(:low)
+  # setting the identifier
+  x.equals(15).identifier('foo')
 end
 ```
 
 But of course with AutoLayout you set up *relationships* between views. Using
 the element-id as a placeholder for a view works especially well here.
 
 ```ruby
 constraints do
-  top_left.equals x: 5, y:5
+  top_left.equals x: 5, y: 5     # this sets the origin relative to the superview
+  top_left.equals(:superview).plus([5, 5])  # this will do the same thing!
+
   width.equals(:foo).minus(10)  # searches for a view named :foo
   height.equals(:foo).minus(10)
   # that's repetitive, so just set 'size'
   size.equals(:foo).minus(10)
   size.equals(:foo).minus([10, 15])  # 10pt thinner, 15pt shorter
+
+  # if you are using a view that has a sensible intrinsic size, like an image,
+  # you can use :scale to have the width or height adjusted according to the
+  # other size
+  width.equals(:superview)
+  height(:scale)  # scale the height according to the width
 end
 ```
 
 Just like with frame helpers you can use the `:element_id` to refer to another
 view, but get this: the view need not be created yet!  This is because when you
@@ -696,9 +734,61 @@
     @layout.add_constraints(self)
     super
   end
 
 end
+```
+
+#### Animating and Changing constraints
+
+It might feel natural to treat constraints as "frame setters", but they are
+persistent objects that are attached to your views.  This means if you create
+new constraints, like during a screen rotation, your old constraints don't “go
+away”.  For example:
+
+```ruby
+def label_style
+  portrait do
+    left 10
+  end
+
+  landscape do
+    left 15  # adds *another* constraint on the left attribute - in addition to the `left 10` constraint!
+  end
+end
+```
+
+Instead, you should retain the constraint and make changes to it directly:
+
+```ruby
+  initial do
+    constraints do
+      @label_left_constraint = left 10
+    end
+  end
+
+  reapply do
+    portrait do
+      @label_left_constraint.equals 10
+    end
+
+    landscape do
+      @label_left_constraint.equals 15
+    end
+  end
+```
+
+If you want to animate a constraint change, you can use `layoutIfNeeded` from
+within a UIView animation block.  The sample app "Chatty" does this to move a
+text field when the keyboard is displayed.  `kbd_height` is the height of the
+keyboard.
+
+```ruby
+@container_bottom.minus kbd_height  # set @container_bottom.constant = 0 when the keyboard disappears
+
+UIView.animateWithDuration(duration, delay: 0, options: curve, animations: -> do
+  self.view.layoutIfNeeded  # applies the constraint change
+end, completion: nil)
 ```
 
 ### MotionKit::Events
 
     gem install motion-kit-events