Update cloneWithProps documentation

Updated documentation to reflect that using React.cloneElement is the new way to copy an element and preserve `key` and `ref`.

Fixes facebook#3432, closes facebook#3447.

Author: mheiber

docs/_data/nav_docs.yml

@@ -56,7 +56,7 @@
     - id: test-utils
       title: Test Utilities
     - id: clone-with-props
-      title: Cloning Components
+      title: Cloning Elements
     - id: create-fragment
       title: Keyed Fragments
     - id: update

docs/docs/10.5-clone-with-props.md

@@ -1,23 +1,34 @@
 ---
 id: clone-with-props
-title: Cloning ReactElement
+title: Cloning ReactElements
 permalink: clone-with-props.html
 prev: test-utils.html
 next: create-fragment.html
 ---
 
-In rare situations an element may want to change the props of an element that it doesn't own (like changing the `className` of an element passed as `this.props.children`). Other times it may want to make multiple copies of an element passed to it. `cloneWithProps()` makes this possible.
+> Note:
+> `cloneWithProps` is deprecated. Use [React.cloneElement](top-level-api.html#react.cloneelement) instead.
 
-#### `ReactElement React.addons.cloneWithProps(ReactElement element, object? extraProps)`
+In rare situations, you may want to create a copy of a React element with different props from those of the original element. One example is cloning the elements passed into `this.props.children` and rendering them with different props:
 
-Do a shallow copy of `element` and merge any props provided by `extraProps`. The `className` and `style` props will be merged intelligently.
+```js
+var _makeBlue = function(element) {
+  return React.addons.cloneWithProps(element, {style: {color: 'blue'}});
+};
 
-> Note:
->
-> `cloneWithProps` does not transfer `key` to the cloned element. If you wish to preserve the key, add it to the `extraProps` object:
->
-> ```js
-> var clonedElement = cloneWithProps(originalElement, { key : originalElement.key });
-> ```
->
-> `ref` is similarly not preserved.
+var Blue = React.createClass({
+  render: function() {
+    var blueChildren = React.Children.map(this.props.children, _makeBlue);
+    return <div>{blueChildren}</div>;
+  }
+});
+
+React.render(
+  <Blue>
+    <p>This text is blue.</p>
+  </Blue>,
+  document.getElementById('container')
+);
+```
+
+`cloneWithProps` does not transfer `key` or `ref` to the cloned element. `className` and `style` props are automatically merged.