[Docs] Add recent addons to addons.html; tweak wording

Add PureRenderMixin and Perf to this page. Also, I think it's better if the link titles reflect the name used by these addons.

(cherry picked from commit d95a4ef)

Author: chenglou

docs/docs/09-addons.md

@@ -9,11 +9,16 @@ next: animation.html
 
 `React.addons` is where we park some useful utilities for building React apps. **These should be considered experimental** but will eventually be rolled into core or a blessed utilities library:
 
-- [`ReactTransitions`](animation.html), for dealing with animations and transitions that are usually not simple to implement, such as before a component's removal.
-- [`ReactLink`](two-way-binding-helpers.html), to simplify the coordination between user's form input data and and the component's state.
-- [`classSet()`](class-name-manipulation.html), for manipulating the DOM `class` string a bit more cleanly.
-- [`ReactTestUtils`](test-utils.html), simple helpers for writing test cases (unminified build only).
-- [`cloneWithProps()`](clone-with-props.html), to make shallow copies of React components and change their props.
-- [`update()`](update.html), a helper function that makes dealing with immutable data in JavaScript easier.
+- [`TransitionGroup` and `CSSTransitionGroup`](animation.html), for dealing with animations and transitions that are usually not simple to implement, such as before a component's removal.
+- [`LinkedStateMixin`](two-way-binding-helpers.html), to simplify the coordination between user's form input data and the component's state.
+- [`classSet`](class-name-manipulation.html), for manipulating the DOM `class` string a bit more cleanly.
+- [`TestUtils`](test-utils.html), simple helpers for writing test cases (unminified build only).
+- [`cloneWithProps`](clone-with-props.html), to make shallow copies of React components and change their props.
+- [`update`](update.html), a helper function that makes dealing with immutable data in JavaScript easier.
+
+The add-ons below are in the development (unminified) version of React only:
+
+- [`PureRenderMixin`](pure-render-mixin.html), a performance booster under certain situations.
+- [`Perf`](perf.html), for measuring performance and giving you hint where to optimize.
 
 To get the add-ons, use `react-with-addons.js` (and its minified counterpart) rather than the common `react.js`.