Update bower install command

Fixes facebook#21

Author: zpao

README.md

@@ -46,7 +46,7 @@ We've also built a [starter kit](http://facebook.github.io/react/downloads/react
 If you'd like to use [bower](http://bower.io), it's as easy as:
 
 ```sh
-bower install react
+bower install --save react
 ```
 
 ## Contribute

docs/downloads.md

@@ -26,7 +26,7 @@ The JSX transformer used to support [XML syntax](/react/docs/syntax.html) in Jav
 ## Bower
 
 ```sh
-$ bower install react
+$ bower install --save react
 ```
 
 ## NPM